Revert "cx20442: tty_ldisc_ops::write_wakeup is optional"

This reverts commit 0e9ffdb2.

It will be coming in through the ASoC tree instead.

Cc: Liam Girdwood <lgirdwood@gmail.com>
Reported-by: Mark Brown <broonie@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: alsa-devel@alsa-project.org
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>