RDMA/mlx5: Use rdma_user_map_io for mapping BAR pages

Since mlx5 supports device disassociate it must use this API for all
BAR page mmaps, otherwise the pages can remain mapped after the device
is unplugged causing a system crash.

Cc: stable@vger.kernel.org
Fixes: 5f9794dc ("RDMA/ucontext: Add a core API for mmaping driver IO memory")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>