Apply compile-time check for AArch64-only cores

Some cores support only AArch64 mode. In those cores, only a limited
subset of the AArch32 system registers are implemented. Hence, if TF-A
is supposed to run on AArch64-only cores, it must be compiled with
CTX_INCLUDE_AARCH32_REGS=0.

Currently, the default settings for compiling TF-A are with the AArch32
system registers included. So, if we compile TF-A the default way and
attempt to run it on an AArch64-only core, we only get a runtime panic.

Now a compile-time check has been added to ensure that this flag has the
appropriate value when AArch64-only cores are included in the build.

Change-Id: I298ec550037fafc9347baafb056926d149197d4c
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index dbc5c21..3cbdfbc 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -96,8 +96,8 @@
 
 ifeq (${ARCH}, aarch64)
 
-# select a different set of CPU files, depending on whether we compile with
-# hardware assisted coherency configurations or not
+# select a different set of CPU files, depending on whether we compile for
+# hardware assisted coherency cores or not
 ifeq (${HW_ASSISTED_COHERENCY}, 0)
 	FVP_CPU_LIBS	+=	lib/cpus/aarch64/cortex_a35.S			\
 				lib/cpus/aarch64/cortex_a53.S			\
@@ -105,14 +105,19 @@
 				lib/cpus/aarch64/cortex_a72.S			\
 				lib/cpus/aarch64/cortex_a73.S
 else
-	FVP_CPU_LIBS	+=	lib/cpus/aarch64/cortex_a55.S			\
-				lib/cpus/aarch64/cortex_a75.S			\
-				lib/cpus/aarch64/cortex_a76.S			\
-				lib/cpus/aarch64/cortex_a76ae.S			\
-				lib/cpus/aarch64/neoverse_n1.S			\
-				lib/cpus/aarch64/neoverse_e1.S			\
-				lib/cpus/aarch64/cortex_deimos.S		\
-				lib/cpus/aarch64/neoverse_zeus.S
+	# AArch64-only cores
+	ifeq (${CTX_INCLUDE_AARCH32_REGS}, 0)
+		FVP_CPU_LIBS	+=	lib/cpus/aarch64/cortex_a76.S		\
+					lib/cpus/aarch64/cortex_a76ae.S		\
+					lib/cpus/aarch64/neoverse_n1.S		\
+					lib/cpus/aarch64/neoverse_e1.S		\
+					lib/cpus/aarch64/cortex_deimos.S	\
+					lib/cpus/aarch64/neoverse_zeus.S
+	# AArch64/AArch32
+	else
+		FVP_CPU_LIBS	+=	lib/cpus/aarch64/cortex_a55.S		\
+					lib/cpus/aarch64/cortex_a75.S
+	endif
 endif
 
 else