hugetlb: take PMD sharing into account when flushing tlb/caches

hugetlb: take PMD sharing into account when flushing tlb/caches

When fixing an issue with PMD sharing and migration, it was discovered
via code inspection that other callers of huge_pmd_unshare potentially
have an issue with cache and tlb flushing.

Use the routine adjust_range_if_pmd_sharing_possible() to calculate
worst case ranges for mmu notifiers.  Ensure that this range is flushed
if huge_pmd_unshare succeeds and unmaps a PUD_SIZE area.

Based on upstream dff11abe280b.  Ported to UEK4.

Orabug: 28951854

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Larry Bassel <larry.bassel@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>