fix(rss): rename AP-RSS message size macro

Adding PLAT_* prefix to indicate that the
platform needs to provide this definition.

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I0bd02be405fd8b1e625bd2b82647ebb2b58265fc
diff --git a/plat/arm/board/fvp/platform.mk b/plat/arm/board/fvp/platform.mk
index 5a21ff6..e9eb261 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -407,8 +407,8 @@
     BL1_SOURCES		+=	${RSS_COMMS_SOURCES}
     BL2_SOURCES		+=	${RSS_COMMS_SOURCES}
 
-    BL1_CFLAGS		+=	-DPLAT_ATTEST_TOKEN_MAX_SIZE=0
-    BL2_CFLAGS		+=	-DPLAT_ATTEST_TOKEN_MAX_SIZE=0
+    BL1_CFLAGS		+=	-DPLAT_RSS_COMMS_PAYLOAD_MAX_SIZE=0
+    BL2_CFLAGS		+=	-DPLAT_RSS_COMMS_PAYLOAD_MAX_SIZE=0
 endif
 
 endif