feat(trbe): enable access to trace buffer control registers from lower NS EL

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

Change-Id: I285a672ccd395eebd377714c992bb21062a729cc
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 1a765e7..9eb66ed 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -22,6 +22,7 @@
 #include <lib/extensions/mpam.h>
 #include <lib/extensions/spe.h>
 #include <lib/extensions/sve.h>
+#include <lib/extensions/trbe.h>
 #include <lib/extensions/twed.h>
 #include <lib/utils.h>
 
@@ -348,6 +349,11 @@
 #if ENABLE_MPAM_FOR_LOWER_ELS
 	mpam_enable(el2_unused);
 #endif
+
+#if ENABLE_TRBE_FOR_NS
+	trbe_enable();
+#endif /* ENABLE_TRBE_FOR_NS */
+
 #endif
 }