refactor(build): avoid using values for comparison

With changes to refactor to use first platform makefiles
then parse arch_features.mk file 'ENABLE_RME' will be initialised
only when we define during build or at arch_features.mk thus
making comparison of 'ENABLE_RME' to '0' incorrect.

So keep BRBE disabled when RME is enabled at main makefile level.

Change-Id: I7e3d99eb444678d63585bd5971ada627cfc4fcc9
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index 165b1610..e21a17e 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -72,9 +72,7 @@
 
 # enable unconditionally for all builds
 ifeq (${ARCH}, aarch64)
-ifeq (${ENABLE_RME},0)
-	ENABLE_BRBE_FOR_NS		:= 2
-endif
+    ENABLE_BRBE_FOR_NS		:= 2
     ENABLE_TRBE_FOR_NS		:= 2
 endif
 ENABLE_SYS_REG_TRACE_FOR_NS	:= 2