arm64: pgtable: Warn unexpected pmdp_test_and_clear_young()

Young bit operation on PMD table entry is only supported if
FEAT_HAFT enabled system wide. Add a warning for notifying
the misbehaviour.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20241102104235.62560-6-yangyicong@huawei.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>