Change Statistical Profiling Extensions build option handling

It is not possible to detect at compile-time whether support for an
optional extension such as SPE should be enabled based on the
ARM_ARCH_MINOR build option value.  Therefore SPE is now enabled by
default.

Change-Id: I670db164366aa78a7095de70a0962f7c0328ab7c
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

docs/user-guide.rst

@@ -344,9 +344,9 @@ Common build options
    the ``ENABLE_PMF`` build option as well. Default is 0.
 
 -  ``ENABLE_SPE_FOR_LOWER_ELS`` : Boolean option to enable Statistical Profiling
-   extensions. This is an optional architectural feature available only for
-   AArch64 8.2 onwards. This option defaults to 1 but is automatically
-   disabled when the target architecture is AArch32 or AArch64 8.0/8.1.
+   extensions. This is an optional architectural feature for AArch64.
+   The default is 1 but is automatically disabled when the target architecture
+   is AArch32.
 
 -  ``ENABLE_STACK_PROTECTOR``: String option to enable the stack protection
    checks in GCC. Allowed values are "all", "strong" and "0" (default).

make_helpers/defaults.mk

@@ -149,19 +149,10 @@ V				:= 0
 # platforms).
 WARMBOOT_ENABLE_DCACHE_EARLY	:= 0
 
-# By default, enable Statistical Profiling Extensions.
-# The top level Makefile will disable this feature depending on
-# the target architecture and version number.
+# Build option to enable/disable the Statistical Profiling Extensions
 ENABLE_SPE_FOR_LOWER_ELS	:= 1
 
-# SPE is enabled by default but only supported on AArch64 8.2 onwards.
-# Disable it in all other cases.
+# SPE is only supported on AArch64 so disable it on AArch32.
 ifeq (${ARCH},aarch32)
     override ENABLE_SPE_FOR_LOWER_ELS := 0
-else
-    ifeq (${ARM_ARCH_MAJOR},8)
-        ifeq ($(ARM_ARCH_MINOR),$(filter $(ARM_ARCH_MINOR),0 1))
-            ENABLE_SPE_FOR_LOWER_ELS := 0
-        endif
-    endif
 endif