feat(brbe): add BRBE support for NS world

This patch enables access to the branch record buffer control registers
in non-secure EL2 and EL1 using the new build option ENABLE_BRBE_FOR_NS.
It is disabled for all secure world, and cannot be used with ENABLE_RME.

This option is disabled by default, however, the FVP platform makefile
enables it for FVP builds.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I576a49d446a8a73286ea6417c16bd0b8de71fca0
diff --git a/bl31/bl31.mk b/bl31/bl31.mk
index 214cf2f..3964469 100644
--- a/bl31/bl31.mk
+++ b/bl31/bl31.mk
@@ -115,6 +115,10 @@
 BL31_SOURCES		+=	lib/extensions/trbe/trbe.c
 endif
 
+ifeq (${ENABLE_BRBE_FOR_NS},1)
+BL31_SOURCES		+=	lib/extensions/brbe/brbe.c
+endif
+
 ifeq (${ENABLE_SYS_REG_TRACE_FOR_NS},1)
 BL31_SOURCES		+=      lib/extensions/sys_reg_trace/aarch64/sys_reg_trace.c
 endif