TTY: serial_core, remove superfluous set_task_state

msleep* is guaranteed to return with TASK_RUNNING task state. And
since there is no other set_task_state in the paths of
uart_wait_until_sent, we need not to set_task_state to TASK_RUNNING.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/serial_core.c

@@ -1414,7 +1414,6 @@ static void __uart_wait_until_sent(struct uart_port *port, int timeout)
 		if (time_after(jiffies, expire))
 			break;
 	}
-	set_current_state(TASK_RUNNING); /* might not be needed */
 }
 
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)