KVM: arm64: Honor UX/PX attributes for EL2 S1 mappings

KVM: arm64: Honor UX/PX attributes for EL2 S1 mappings

Now that we potentially have two bits to deal with when setting
execution permissions, make sure we correctly handle them when both
when building the page tables and when reading back from them.

Reported-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20251210173024.561160-7-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>