scsi: mpt3sas: Make mpt3sas_dev_attrs static

scsi: mpt3sas: Make mpt3sas_dev_attrs static

This symbol is not used outside of mpt3sas_ctl.c, mark it static.

Fixes the following sparse warning:

drivers/scsi/mpt3sas/mpt3sas_ctl.c:3988:18: warning: symbol
'mpt3sas_dev_attrs' was not declared. Should it be static?

Link: https://lore.kernel.org/r/1634639239-2892-1-git-send-email-jiapeng.chong@linux.alibaba.com
Fixes: 19e78123eedf ("scsi: mpt3sas: Switch to attribute groups")
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>