ALSA: hda - Clearing jackpoll_interval avoid pending work

Clearing jackpoll_interval before calling cancel_delayed_work_sync(),
otherwise the work will be triggered again and cause impact in
hda_jackpoll_work(). The next patch will poll jack once even with
jackpoll_interval=0.

Signed-off-by: Wang Xingchao <xingchao.wang@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>