scsi: pm80xx: Display proc_name in sysfs

scsi: pm80xx: Display proc_name in sysfs

The proc_name entry in sysfs for pm80xx is "(null)" because it is not
initialized in scsi_host_template:

Before:
host:~# cat /sys/class/scsi_host/host6/proc_name
(null)

After:
host:~# cat /sys/class/scsi_host/host6/proc_name
pm80xx

Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Link: https://lore.kernel.org/r/20221007230651.308969-1-ipylypiv@google.com
Reviewed-by: Jolly Shah <jollys@google.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>