display the following device information under /sys/class/infiniband/mlx4_X:
board_id, fw_ver, hw_rev, hca_type.

This patch makes this information available to userspace utilities
such as ibstat and ibv_devinfo.
Signed-off-by: NJack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>