aarch64: Enable Statistical Profiling Extensions for lower ELs

SPE is only supported in non-secure state.  Accesses to SPE specific
registers from SEL1 will trap to EL3.  During a world switch, before
`TTBR` is modified the SPE profiling buffers are drained.  This is to
avoid a potential invalid memory access in SEL1.

SPE is architecturally specified only for AArch64.

Change-Id: I04a96427d9f9d586c331913d815fdc726855f6b0
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
diff --git a/Makefile b/Makefile
index aec10c9..31964de 100644
--- a/Makefile
+++ b/Makefile
@@ -454,6 +454,7 @@
 $(eval $(call assert_boolean,USE_COHERENT_MEM))
 $(eval $(call assert_boolean,USE_TBBR_DEFS))
 $(eval $(call assert_boolean,WARMBOOT_ENABLE_DCACHE_EARLY))
+$(eval $(call assert_boolean,ENABLE_SPE_FOR_LOWER_ELS))
 
 $(eval $(call assert_numeric,ARM_ARCH_MAJOR))
 $(eval $(call assert_numeric,ARM_ARCH_MINOR))
@@ -493,6 +494,7 @@
 $(eval $(call add_define,USE_COHERENT_MEM))
 $(eval $(call add_define,USE_TBBR_DEFS))
 $(eval $(call add_define,WARMBOOT_ENABLE_DCACHE_EARLY))
+$(eval $(call add_define,ENABLE_SPE_FOR_LOWER_ELS))
 
 # Define the EL3_PAYLOAD_BASE flag only if it is provided.
 ifdef EL3_PAYLOAD_BASE