IB: Replace ib_umem page_size by page_shift

Size of pages are held by struct ib_umem in page_size field.

It is better to store it as an exponent, because page size by nature
is always power-of-two and used as a factor, divisor or ilog2's argument.

The conversion of page_size to be page_shift allows to have portable
code and avoid following error while compiling on ARM:

  ERROR: "__aeabi_uldivmod" [drivers/infiniband/core/ib_core.ko] undefined!

CC: Selvin Xavier <selvin.xavier@broadcom.com>
CC: Steve Wise <swise@chelsio.com>
CC: Lijun Ou <oulijun@huawei.com>
CC: Shiraz Saleem <shiraz.saleem@intel.com>
CC: Adit Ranadive <aditr@vmware.com>
CC: Dennis Dalessandro <dennis.dalessandro@intel.com>
CC: Ram Amrani <Ram.Amrani@Cavium.com>
Signed-off-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Acked-by: Ram Amrani <Ram.Amrani@cavium.com>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
Acked-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/mem.c

@@ -59,7 +59,7 @@ void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr,
 	u64 pfn;
 	struct scatterlist *sg;
 	int entry;
-	unsigned long page_shift = ilog2(umem->page_size);
+	unsigned long page_shift = umem->page_shift;
 
 	/* With ODP we must always match OS page size. */
 	if (umem->odp_data) {
@@ -156,7 +156,7 @@ void __mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
 			    int page_shift, size_t offset, size_t num_pages,
 			    __be64 *pas, int access_flags)
 {
-	unsigned long umem_page_shift = ilog2(umem->page_size);
+	unsigned long umem_page_shift = umem->page_shift;
 	int shift = page_shift - umem_page_shift;
 	int mask = (1 << shift) - 1;
 	int i, k, idx;