feat(trbe): add trbe under feature detection mechanism

This change adds "FEAT_TRBE" to be part of feature detection mechanism.

Previously feature enablement flags were of boolean type, containing
either 0 or 1. With the introduction of feature detection procedure
we now support three states for feature enablement build flags(0 to 2).

Accordingly, "ENABLE_TRBE_FOR_NS" flag is now modified from boolean
to numeric type to align with the feature detection.

Change-Id: I53d3bc8dc2f6eac63feef22dfd627f3a48480afc
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
diff --git a/common/feat_detect.c b/common/feat_detect.c
index 9d0685b..be3e20e 100644
--- a/common/feat_detect.c
+++ b/common/feat_detect.c
@@ -244,6 +244,16 @@
 #endif
 }
 
+/******************************************************
+ * Feature : FEAT_TRBE (Trace Buffer Extension)
+ *****************************************************/
+static void read_feat_trbe(void)
+{
+#if (ENABLE_TRBE_FOR_NS == FEAT_STATE_1)
+	feat_detect_panic(is_feat_trbe_present(), "TRBE");
+#endif
+}
+
 /***********************************************************************************
  * TF-A supports many Arm architectural features starting from arch version
  * (8.0 till 8.7+). These features are mostly enabled through build flags. This
@@ -306,6 +316,7 @@
 
 	/* v9.0 features */
 	read_feat_brbe();
+	read_feat_trbe();
 
 	/* v9.2 features */
 	read_feat_rme();