mm/hmm: remove the mask variable in hmm_vma_walk_hugetlb_entry

The pagewalk code already passes the value as the hmask parameter.

Link: https://lore.kernel.org/r/20190806160554.14046-9-hch@lst.de


Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>