n_tty: Unthrottle tty when flushing read buffer

When the tty input buffer is full and thereby throttled,
flushing/resetting the read buffer should unthrottle to allow more
data to be received.

Signed-off-by: Karthik Manamcheri <Karthik.Manamcheri@ni.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_tty.c

@@ -229,6 +229,8 @@ static void reset_buffer_flags(struct tty_struct *tty)
 	ldata->canon_head = ldata->canon_data = ldata->erasing = 0;
 	bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
 	n_tty_set_room(tty);
+
+	check_unthrottle(tty);
 }
 
 /**