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.comReported-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>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -3480,7 +3480,7 @@ static ssize_t ibmvfc_read_trace(struct file *filp, struct kobject *kobj,
 				 struct bin_attribute *bin_attr,
 				 char *buf, loff_t off, size_t count)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct Scsi_Host *shost = class_to_shost(dev);
 	struct ibmvfc_host *vhost = shost_priv(shost);
 	unsigned long flags = 0;