dm: serial: Correct logic in serial_find_console_or_panic()

In a final attempt to find a console UART this function uses the first
first available serial device. However the check for a valid device is
inverted.

This code is only executed when there is in fact no serial UART, but at
present it can fail to reach the panic_str() call in this case, and start
trying to use a non-existent UART.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/serial/serial-uclass.c

@@ -71,7 +71,7 @@ static void serial_find_console_or_panic(void)
 #endif
 		if (!uclass_get_device_by_seq(UCLASS_SERIAL, INDEX, &dev) ||
 		    !uclass_get_device(UCLASS_SERIAL, INDEX, &dev) ||
-		    (!uclass_first_device(UCLASS_SERIAL, &dev) || dev)) {
+		    (!uclass_first_device(UCLASS_SERIAL, &dev) && dev)) {
 			gd->cur_serial_dev = dev;
 			return;
 		}