KVM: arm64: Use generic sanitisation for ID_(AA64)DFR0_EL1

KVM allows userspace to specify a PMU version for the guest by writing
to the corresponding ID registers. Currently the validation of these
writes is done manuallly, but there's no reason we can't switch over to
the generic sanitisation infrastructure.

Start screening user writes through arm64_check_features() to prevent
userspace from over-promising in terms of vPMU support. Leave the old
masking in place for now, as we aren't completely ready to serve reads
from the VM-wide values.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
Link: https://lore.kernel.org/r/20230609190054.1542113-9-oliver.upton@linux.dev


[Oliver: split off from monster patch, cleaned up handling of NI vPMU
 values, wrote commit description]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>