feat(trf): enable trace filter control register access from lower NS EL

Introduced a build flag 'ENABLE_TRF_FOR_NS' to enable trace filter
control registers access in NS-EL2, or NS-EL1 (when NS-EL2 is
implemented but unused).

Change-Id: If3f53b8173a5573424b9a405a4bd8c206ffdeb8c
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/bl32/sp_min/sp_min.mk b/bl32/sp_min/sp_min.mk
index 486d39d..6339cf8 100644
--- a/bl32/sp_min/sp_min.mk
+++ b/bl32/sp_min/sp_min.mk
@@ -46,6 +46,10 @@
 BL32_SOURCES		+=	lib/extensions/sys_reg_trace/aarch32/sys_reg_trace.c
 endif
 
+ifeq (${ENABLE_TRF_FOR_NS},1)
+BL32_SOURCES		+=	lib/extensions/trf/aarch32/trf.c
+endif
+
 BL32_LINKERFILE	:=	bl32/sp_min/sp_min.ld.S
 
 # Include the platform-specific SP_MIN Makefile