When scanning devices through the 'scan' attribute in sysfs, the user will
observe duplicate device entries in lsscsi command output.

Set the shost's max_channel to zero to avoid this.

Link: https://lore.kernel.org/r/20211014055425.30719-1-sreekanth.reddy@broadcom.com
Fixes: 824a1566 ("scsi: mpi3mr: Base driver code")
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>