fix(cpufeat): add feat_hcx check before enabling FEAT_MOPS

This patch also checks for FEAT_HCX before enabling FEAT_MOPS
when INIT_UNUSED_NS_EL1 = 1 and adds build dependency check.

Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: Iff4a068aa392fc8d29e2e4da7a2e7df0b3104e65
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index c35aae9..d870da4 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -905,7 +905,7 @@
 		sme_init_el2_unused();
 	}
 
-	if (is_feat_mops_supported()) {
+	if (is_feat_mops_supported() && is_feat_hcx_supported()) {
 		write_hcrx_el2(read_hcrx_el2() | HCRX_EL2_MSCEn_BIT);
 	}