KVM: arm64: Account for RES1 bits in DECLARE_FEAT_MAP() and co

None of the registers we manage in the feature dependency infrastructure
so far has any RES1 bit. This is about to change, as VTCR_EL2 has
its bit 31 being RES1.

In order to not fail the consistency checks by not describing a bit,
add RES1 bits to the set of immutable bits. This requires some extra
surgery for the FGT handling, as we now need to track RES1 bits there
as well.

There are no RES1 FGT bits *yet*. Watch this space.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20251210173024.561160-5-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_host.h

@@ -638,6 +638,7 @@ struct fgt_masks {
 	u64		mask;
 	u64		nmask;
 	u64		res0;
+	u64		res1;
 };
 
 extern struct fgt_masks hfgrtr_masks;