[media] cec: set timestamp for selfie transmits

Attempts to send CEC messages to yourself are detected in the framework and
returned with a NACK error. However, the tx_ts was never filled in that case.
So just set it.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/cec/cec-adap.c

@@ -603,6 +603,7 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 			 * easy to handle it here so the behavior will be
 			 * consistent.
 			 */
+			msg->tx_ts = ktime_get_ns();
 			msg->tx_status = CEC_TX_STATUS_NACK |
 					 CEC_TX_STATUS_MAX_RETRIES;
 			msg->tx_nack_cnt = 1;