net/mlx5_core: Add setting ATOMIC endian mode

HW is capable of 2 requestor endianness modes for standard 8 Bytes
atomic: BE (0x0) and host endianness (0x1). Read the supported modes
from hca atomic capabilities and configure HW to host endianness mode if
supported.

Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>