arm64/mm: Override ptep_get_lockless_norecency()

Override ptep_get_lockless_norecency() when CONFIG_ARM64_CONTPTE is
enabled. Because this API doesn't require the access and dirty bits to
be accurate, for the contpte case, we can avoid reading all ptes in the
contpte block to collect those bits, in contrast to ptep_get_lockless().

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>