The bsg_setup_queue() function does not return NULL.  It returns error
pointers.  Fix the check accordingly.

Link: https://lore.kernel.org/r/YnUf7RQl+A3tigWh@kili
Fixes: 4268fa75 ("scsi: mpi3mr: Add bsg device support")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>