Move ARM_ARCH_MINOR down to 5 as GCC9.2 (used by CI) only supports up to v8.5

Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Change-Id: Ib6b79941192216dc4c2655ab53ea4814f1102ad2
diff --git a/tf_config/fvp-mtpmu-disable b/tf_config/fvp-mtpmu-disable
index 4249512..130d164 100644
--- a/tf_config/fvp-mtpmu-disable
+++ b/tf_config/fvp-mtpmu-disable
@@ -1,4 +1,4 @@
-ARM_ARCH_MINOR=6
+ARM_ARCH_MINOR=5
 CROSS_COMPILE=aarch64-none-elf-
 DISABLE_MTPMU=1
 PLAT=fvp