RDMA/i40iw: Use core helpers to get aligned DMA address within a supported page size

Call the core helpers to retrieve the HW aligned address to use for the
MR, within a supported i40iw page size.

Remove code in i40iw to determine when MR is backed by 2M huge pages which
involves checking the umem->hugetlb flag and VMA inspection.  The new DMA
iterator will return the 2M aligned address if the MR is backed by 2M
pages.

Fixes: f26c7c83

 ("i40iw: Add 2MB page support")
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>