refactor(build): move SVE_VECTOR_LEN flag to add_defines section

Presently, we have an explicit section to add definitions, wherein
we evaluate the definitions after being overwritten by the platform.

To keep it aligned with this pattern, SVE_VECTOR_LEN is moved here.

Change-Id: Ia3373d954a7ee97980fe72d5a069e202352f25b1
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
diff --git a/Makefile b/Makefile
index 2b2f79e..03f9320 100644
--- a/Makefile
+++ b/Makefile
@@ -1040,9 +1040,6 @@
 # Determine if FEAT_SB is supported
 ENABLE_FEAT_SB		=	$(if $(findstring sb,${arch-features}),1,0)
 
-#SVE_VECTOR_LEN
-$(eval $(call add_define,SVE_VECTOR_LEN))
-
 ################################################################################
 # Process platform overrideable behaviour
 ################################################################################
@@ -1407,6 +1404,7 @@
 	ENABLE_FEAT_TWED \
 	CONDITIONAL_CMO \
 	IMPDEF_SYSREG_TRAP \
+	SVE_VECTOR_LEN \
 )))
 
 ifeq (${SANITIZE_UB},trap)