scsi: fnic: Remove set but not used 'fr_len'

This addresses the following gcc warning with "make W=1":

drivers/scsi/fnic/fnic_fcs.c: In function ‘fnic_fcoe_send_vlan_req’:
drivers/scsi/fnic/fnic_fcs.c:379:6: warning: variable ‘fr_len’ set but
not used [-Wunused-but-set-variable]
  379 |  int fr_len;
      |      ^~~~~~

Link: https://lore.kernel.org/r/20200831081126.3251288-4-yanaijie@huawei.comReported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/fnic/fnic_fcs.c

@@ -372,7 +372,6 @@ static void fnic_fcoe_send_vlan_req(struct fnic *fnic)
 	struct fnic_stats *fnic_stats = &fnic->fnic_stats;
 	struct sk_buff *skb;
 	char *eth_fr;
-	int fr_len;
 	struct fip_vlan *vlan;
 	u64 vlan_tov;
 
@@ -387,7 +386,6 @@ static void fnic_fcoe_send_vlan_req(struct fnic *fnic)
 	if (!skb)
 		return;
 
-	fr_len = sizeof(*vlan);
 	eth_fr = (char *)skb->data;
 	vlan = (struct fip_vlan *)eth_fr;