KVM: arm64: Allow guest to set the OSLK bit

Allow writes to OSLAR and forward the OSLK bit to OSLSR. Do nothing with
the value for now.

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220203174159.2887882-4-oupton@google.com