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: c4f7ac64 ("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.comReviewed-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>

drivers/scsi/mpi3mr/Makefile

 # mpi3mr makefile
-obj-m += mpi3mr.o
+obj-$(CONFIG_SCSI_MPI3MR) += mpi3mr.o
 mpi3mr-y +=  mpi3mr_os.o     \
 		mpi3mr_fw.o \
 		mpi3mr_app.o \