Added flush_scheduled_work() in snd_hda_codec_free() to make sure that
the all work is gone.  Also, optimized the condition to schedule the
delayed work in snd_hda_power_down().
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>