KVM: arm64: Allow RES1 bits to be inferred from configuration

KVM: arm64: Allow RES1 bits to be inferred from configuration

So far, when a bit field is tied to an unsupported feature, we set
it as RES0. This is almost correct, but there are a few exceptions
where the bits become RES1.

Add a AS_RES1 qualifier that instruct the RESx computing code to
simply do that.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260202184329.2724080-8-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>