mm/page_vma_mapped.c: use helper function huge_pte_lock

Use helper function huge_pte_lock() to lock the huge pte to simplify the
code a bit.  No functional change intended.

Link: https://lkml.kernel.org/r/20220709092440.43018-1-linmiaohe@huawei.com


Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>