test(realm): Use new build flag for Realm tests

Use new build flag ENABLE_REALM_PAYLOAD_TESTS=1
for realm payload tests.

Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
Change-Id: I83b0a069351210437def177370e7d4621b3aab03
diff --git a/tftf_config/fvp-rme b/tftf_config/fvp-rme
new file mode 100644
index 0000000..2f2586c
--- /dev/null
+++ b/tftf_config/fvp-rme
@@ -0,0 +1,3 @@
+CROSS_COMPILE=aarch64-none-elf-
+PLAT=fvp
+ENABLE_REALM_PAYLOAD_TESTS=1