IB/mlx5: Avoid load failure due to unknown link width

commit db7a691a1551a748cb92d9c89c6b190ea87e28d5 upstream.

If the firmware reports a connection width that is not 1x, 4x, 8x or 12x
it causes the driver to fail during initialization.

To prevent this failure every time a new width is introduced to the RDMA
stack, we will set a default 4x width for these widths which ar unknown to
the driver.

This is needed to allow to run old kernels with new firmware.

Cc: <stable@vger.kernel.org> # 4.1
Fixes: 1b5daf11 ("IB/mlx5: Avoid using the MAD_IFC command under ISSI > 0 mode")
Signed-off-by: Michael Guralnik <michaelgur@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>