scsi: snic: Fix possible UAF in snic_tgt_create()

Smatch reports a warning as follows:

drivers/scsi/snic/snic_disc.c:307 snic_tgt_create() warn:
'&tgt->list' not removed from list

If device_add() fails in snic_tgt_create(), tgt will be freed, but
tgt->list will not be removed from snic->disc.tgt_list, then list traversal
may cause UAF.

Remove from snic->disc.tgt_list before free().

Fixes: c8806b6c9e82 ("snic: driver for Cisco SCSI HBA")
Signed-off-by: Gaosheng Cui <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Acked-by: Narsimhulu Musini <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/snic/snic_disc.c

···
 			      ret);
 
 		put_device(&snic->shost->shost_gendev);
+		spin_lock_irqsave(snic->shost->host_lock, flags);
+		list_del(&tgt->list);
+		spin_unlock_irqrestore(snic->shost->host_lock, flags);
 		kfree(tgt);
 		tgt = NULL;