net: tftpput: reset timeout_count when an ACK is received

timeout_count is never reset once a tftpput transfer has started. If for
whatever reason timeouts occur frequently, but the server keeps replying
nonetheless, the transfer may be needlessly aborted.

Reset timer_count on reception of an ACK to avoid this situation.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
diff --git a/net/tftp.c b/net/tftp.c
index 8f94820..fd9c9492 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -478,6 +478,7 @@
 	case TFTP_ACK:
 #ifdef CONFIG_CMD_TFTPPUT
 		if (tftp_put_active) {
+			timeout_count = 0;
 			if (tftp_put_final_block_sent) {
 				tftp_complete();
 			} else {