fix(ci): downgrade ARM_ARCH_MAJOR and ARM_ARCH_MINOR on generic build configs

This directly propagates to the -march directive which enables the use
of architectural features. The fvp-spm-sve+sme build config may or may
not be run in a model with these features enabled. So don't specify
them so we don't get faults in random places.

But keep it at a reasonable minimum, so that we get BIT land pads.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I1668ba753a14149431bd8ed63e153e112056475e
diff --git a/tf_config/fvp-spm-sve+sme b/tf_config/fvp-spm-sve+sme
index 3834d98..eebe2d3 100644
--- a/tf_config/fvp-spm-sve+sme
+++ b/tf_config/fvp-spm-sve+sme
@@ -1,5 +1,5 @@
-ARM_ARCH_MAJOR=9
-ARM_ARCH_MINOR=4
+ARM_ARCH_MAJOR=8
+ARM_ARCH_MINOR=5
 BRANCH_PROTECTION=1
 CROSS_COMPILE=aarch64-none-elf-
 CTX_INCLUDE_AARCH32_REGS=0