Remove incorrect and redundant wait_until_sent operation, which waits
for the driver buffer rather than any hardware buffers to drain,
something which is already taken care of by the tty layer (and
chars_in_buffer).
Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>