feat(mte): add mte2 feat

Add support for feat mte2. tfsr_el2 is available only with mte2,
however currently its context_save/restore is done with mte rather than
mte2, so introduce 'is_feat_mte2_supported' to check mte2.

Change-Id: I108d9989a8f5b4d1d2f3b9865a914056fa566cf2
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/Makefile b/Makefile
index c1448fa..f324ebc 100644
--- a/Makefile
+++ b/Makefile
@@ -1246,6 +1246,7 @@
 	ENABLE_FEAT_FGT \
 	ENABLE_FEAT_HCX \
 	ENABLE_FEAT_MTE \
+	ENABLE_FEAT_MTE2 \
 	ENABLE_FEAT_PAN \
 	ENABLE_FEAT_RNG \
 	ENABLE_FEAT_RNG_TRAP \
@@ -1406,6 +1407,7 @@
 	ENABLE_FEAT_S1POE \
 	ENABLE_FEAT_GCS \
 	ENABLE_FEAT_MTE \
+	ENABLE_FEAT_MTE2 \
 	ENABLE_FEAT_MTE_PERM \
 	FEATURE_DETECTION \
 	TWED_DELAY \