KVM: arm64: Use KVM's pte type/helpers in handle_access_fault()

Consistently use KVM's own pte types and helpers in
handle_access_fault().

No functional change intended.

Link: https://lore.kernel.org/r/20221202185156.696189-2-oliver.upton@linux.dev


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>