scsi: be2iscsi: Add checks to validate CID alloc/free

Set CID slot to 0xffff to indicate empty.
Check if connection already exists in conn_table before binding.
Check if endpoint already NULL before putting back CID.
Break ep->conn link in free_ep to ignore completions after freeing.

Signed-off-by: Jitendra Bhivare <jitendra.bhivare@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/be2iscsi/be_main.h

@@ -343,6 +343,7 @@ struct beiscsi_hba {
 	spinlock_t async_pdu_lock;
 	struct list_head hba_queue;
 #define BE_MAX_SESSION 2048
+#define BE_INVALID_CID 0xffff
 #define BE_SET_CID_TO_CRI(cri_index, cid) \
 			  (phba->cid_to_cri_map[cid] = cri_index)
 #define BE_GET_CRI_FROM_CID(cid) (phba->cid_to_cri_map[cid])