scsi: mpi3mr: Refer CONFIG_SCSI_MPI3MR in Makefile

scsi: mpi3mr: Refer CONFIG_SCSI_MPI3MR in Makefile

When Kconfig item CONFIG_SCSI_MPI3MR was introduced for mpi3mr driver, the
Makefile of the driver was not modified to refer the Kconfig item.

As a result, mpi3mr.ko is built regardless of the Kconfig item value y or
m. Also, if 'make localmodconfig' can not find the Kconfig item in the
Makefile, then it does not generate CONFIG_SCSI_MPI3MR=m even when
mpi3mr.ko is loaded on the system.

Refer to the Kconfig item to avoid the issues.

Fixes: c4f7ac64616e ("scsi: mpi3mr: Add mpi30 Rev-R headers and Kconfig")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20221207023659.2411785-1-shinichiro.kawasaki@wdc.com
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>