refactor(build): remove enabling feat

All mandatory FEAT_* enabling is done from arch_features.mk.
Remove some old code which would enable some mandatory options based
on arch-features option passed to march appending.

This is now not needed anymore since if we are using correct
ARCH_MAJOR/MINOR the mandatory options will taken care from
arch_features.mk

Change-Id: I8565ac4ebb3ced29835be65ea5b043a08810872f
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/Makefile b/Makefile
index 2967195..fc41697 100644
--- a/Makefile
+++ b/Makefile
@@ -1029,12 +1029,6 @@
 	endif
 endif
 
-# Determine if FEAT_RNG is supported
-ENABLE_FEAT_RNG		=	$(if $(findstring rng,${arch-features}),1,0)
-
-# Determine if FEAT_SB is supported
-ENABLE_FEAT_SB		=	$(if $(findstring sb,${arch-features}),1,0)
-
 ifeq ($(PSA_CRYPTO),1)
         $(info PSA_CRYPTO is an experimental feature)
 endif
@@ -1160,7 +1154,6 @@
 	ENABLE_AMU_FCONF \
 	AMU_RESTRICT_COUNTERS \
 	ENABLE_ASSERTIONS \
-	ENABLE_FEAT_SB \
 	ENABLE_PIE \
 	ENABLE_PMF \
 	ENABLE_PSCI_STAT \
@@ -1257,6 +1250,7 @@
 	ENABLE_FEAT_RNG_TRAP \
 	ENABLE_FEAT_SEL2 \
 	ENABLE_FEAT_TCR2 \
+	ENABLE_FEAT_SB \
 	ENABLE_FEAT_S2PIE \
 	ENABLE_FEAT_S1PIE \
 	ENABLE_FEAT_S2POE \