refactor(FF-A): add macros for defining FF-A versions

Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
Change-Id: Icec0a68f60252d9cdeb41dd86bc1ae8b6acf0761
diff --git a/src/api.c b/src/api.c
index 9510042..38475a7 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1632,9 +1632,7 @@
 		return (struct ffa_value){.func = (uint32_t)FFA_NOT_SUPPORTED};
 	}
 
-	return (struct ffa_value){
-		.func = (FFA_VERSION_MAJOR << FFA_VERSION_MAJOR_OFFSET) |
-			FFA_VERSION_MINOR};
+	return ((struct ffa_value){.func = FFA_VERSION_COMPILED});
 }
 
 int64_t api_debug_log(char c, struct vcpu *current)