scsi: ibmvfc: Switch to using kobj_to_dev()

Fix the following coccicheck warnings:

./drivers/scsi/ibmvscsi/ibmvfc.c:3483:60-61: WARNING opportunity for
kobj_to_dev().

Link: https://lore.kernel.org/r/1614850124-54111-1-git-send-email-jiapeng.chong@linux.alibaba.com


Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Acked-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>