doc: Fix variables names in TBBR CoT documentation

In commit 516beb58

 ("TBB: apply TBBR naming
convention to certificates and extensions"), some of the variables used in the
TBBR chain of trust got renamed but the documentation did not get properly
updated everywhere to reflect these changes.

Change-Id: Ie8e2146882c2d3538c5b8c968d1bdaf5ea2a6e53
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

docs/design/auth-framework.rst

@@ -621,7 +621,7 @@ The TBBR CoT
 
 The CoT can be found in ``drivers/auth/tbbr/tbbr_cot.c``. This CoT consists of
 an array of pointers to image descriptors and it is registered in the framework
-using the macro ``REGISTER_COT(cot_desc)``, where 'cot_desc' must be the name
+using the macro ``REGISTER_COT(cot_desc)``, where ``cot_desc`` must be the name
 of the array (passing a pointer or any other type of indirection will cause the
 registration process to fail).
 
@@ -870,32 +870,32 @@ Once the signature has been checked and the certificate authenticated, the
 Trusted World public key needs to be extracted from the certificate. A new entry
 is created in the ``authenticated_data`` array for that purpose. In that entry,
 the corresponding parameter descriptor must be specified along with the buffer
-address to store the parameter value. In this case, the ``tz_world_pk`` descriptor
-is used to extract the public key from an x509v3 extension with OID
+address to store the parameter value. In this case, the ``trusted_world_pk``
+descriptor is used to extract the public key from an x509v3 extension with OID
 ``TRUSTED_WORLD_PK_OID``. The BL31 key certificate will use this descriptor as
 parameter in the signature authentication method. The key is stored in the
-``plat_tz_world_pk_buf`` buffer.
+``trusted_world_pk_buf`` buffer.
 
 The **BL31 Key certificate** is authenticated by checking its digital signature
 using the Trusted World public key obtained previously from the Trusted Key
 certificate. In the image descriptor, we specify a single authentication method
-by signature whose public key is the ``tz_world_pk``. Once this certificate has
-been authenticated, we have to extract the BL31 public key, stored in the
-extension specified by ``bl31_content_pk``. This key will be copied to the
-``plat_content_pk`` buffer.
+by signature whose public key is the ``trusted_world_pk``. Once this certificate
+has been authenticated, we have to extract the BL31 public key, stored in the
+extension specified by ``soc_fw_content_pk``. This key will be copied to the
+``content_pk_buf`` buffer.
 
 The **BL31 certificate** is authenticated by checking its digital signature
 using the BL31 public key obtained previously from the BL31 Key certificate.
-We specify the authentication method using ``bl31_content_pk`` as public key.
+We specify the authentication method using ``soc_fw_content_pk`` as public key.
 After authentication, we need to extract the BL31 hash, stored in the extension
-specified by ``bl31_hash``. This hash will be copied to the ``plat_bl31_hash_buf``
-buffer.
+specified by ``soc_fw_hash``. This hash will be copied to the
+``soc_fw_hash_buf`` buffer.
 
 The **BL31 image** is authenticated by calculating its hash and matching it
 with the hash obtained from the BL31 certificate. The image descriptor contains
 a single authentication method by hash. The parameters to the hash method are
-the reference hash, ``bl31_hash``, and the data to be hashed. In this case, it is
-the whole image, so we specify ``raw_data``.
+the reference hash, ``soc_fw_hash``, and the data to be hashed. In this case,
+it is the whole image, so we specify ``raw_data``.
 
 The image parser library
 ~~~~~~~~~~~~~~~~~~~~~~~~
@@ -965,6 +965,6 @@ The mbedTLS library algorithm support is configured by both the
 
 --------------
 
-*Copyright (c) 2017-2019, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2017-2020, Arm Limited and Contributors. All rights reserved.*
 
 .. _TBBR-Client specification: https://developer.arm.com/docs/den0006/latest/trusted-board-boot-requirements-client-tbbr-client-armv8-a