[nrf fromlist] net: openthread: Remove waiting for DTR in openthread UART.

Uart driver for openthread have been waiting for host to start
communicating with coprocessor, during booting of the Zephyr and
by that blocking start os OS. There is no longer a need for
that since the stack will be soft rebooted after host connects
to coprocessor, removing the need to wait on host communication.

Upstream PR: zephyrproject-rtos/zephyr#63355

Signed-off-by: Przemyslaw Bida <[email protected]>
(cherry picked from commit cc85223)

Author: Przemyslaw Bida

modules/openthread/platform/uart.c

@@ -170,28 +170,13 @@ otError otPlatUartEnable(void)
 
 	if (DT_NODE_HAS_COMPAT(DT_CHOSEN(zephyr_ot_uart), zephyr_cdc_acm_uart)) {
 		int ret;
-		uint32_t dtr = 0U;
 
 		ret = usb_enable(NULL);
 		if (ret != 0 && ret != -EALREADY) {
 			LOG_ERR("Failed to enable USB");
 			return OT_ERROR_FAILED;
 		}
 
-		LOG_INF("Waiting for host to be ready to communicate");
-
-		/* Data Terminal Ready - check if host is ready to communicate */
-		while (!dtr) {
-			ret = uart_line_ctrl_get(ot_uart.dev,
-						 UART_LINE_CTRL_DTR, &dtr);
-			if (ret) {
-				LOG_ERR("Failed to get Data Terminal Ready line state: %d",
-					ret);
-				continue;
-			}
-			k_msleep(100);
-		}
-
 		/* Data Carrier Detect Modem - mark connection as established */
 		(void)uart_line_ctrl_set(ot_uart.dev, UART_LINE_CTRL_DCD, 1);
 		/* Data Set Ready - the NCP SoC is ready to communicate */