IB/mlx5: Fix out-of-bound access

When we initialize buffer to create SRQ in kernel,
the number of pages was less than actually used in
following mlx5_fill_page_array().

Fixes: e126ba97 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>