In the case where mbox_status is OCRDMA_MBX_STATUS_FAILED and
add_status is OCRDMA_MBX_STATUS_FAILED err_num is assigned -EAGAIN
however the case OCRDMA_MBX_STATUS_FAILED is missing a break and
falls through to the default case which then re-assigns err_num
to -EFAULT.   Fix this so that err_num is assigned to -EAGAIN
for the add_status OCRDMA_MBX_STATUS_FAILED case and -EFAULT
otherwise.

Detected by CoverityScan CID#703125 ("Missing break in switch")

Fixes: fe2caefc ("RDMA/ocrdma: Add driver for Emulex OneConnect IBoE RDMA adapter")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>