KVM: arm64: PSCI: Narrow input registers when using 32bit functions
When a guest delibarately uses an SMC32 function number (which is allowed),
we should make sure we drop the top 32bits from the input arguments, as they
could legitimately be junk.
Reported-by: Christoffer Dall <christoffer.dall@arm.com> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org>