scsi: mpi3mr: Fix a NULL vs IS_ERR() bug in mpi3mr_bsg_init()

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: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>