doc: Fixup some SMCCC links

This is a fixup for patch 3ba55a3c


("docs: Update SMCCC doc, other changes for release"), where some
links names got changed but their references didn't.

Change-Id: I980d04dde338f3539a2ec1ae2e807440587b1cf5
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

docs/components/debugfs-design.rst

@@ -78,7 +78,7 @@ SMC interface
 -------------
 
 The communication with the 9p layer in BL31 is made through an SMC conduit
-(`SMC Calling Convention PDD`_), using a specific SiP Function Id. An NS
+(`SMC Calling Convention`_), using a specific SiP Function Id. An NS
 shared buffer is used to pass path string parameters, or e.g. to exchange
 data on a read operation. Refer to `ARM SiP Services`_ for a description
 of the SMC interface.

docs/design/firmware-design.rst

@@ -544,7 +544,7 @@ It then replaces the exception vectors populated by BL1 with its own. BL31
 exception vectors implement more elaborate support for handling SMCs since this
 is the only mechanism to access the runtime services implemented by BL31 (PSCI
 for example). BL31 checks each SMC for validity as specified by the
-`SMC Calling Convention PDD`_ before passing control to the required SMC
+`SMC Calling Convention`_ before passing control to the required SMC
 handler routine.
 
 BL31 programs the ``CNTFRQ_EL0`` register with the clock frequency of the system
@@ -2711,7 +2711,7 @@ kernel at boot time. These can be found in the ``fdts`` directory.
 
 -  `Power State Coordination Interface PDD`_
 
--  `SMC Calling Convention PDD`_
+-  `SMC Calling Convention`_
 
 -  :ref:`Interrupt Management Framework`