ALSA: oxygen: use true,false for bool variables

Fix the following coccicheck warning:

sound/pci/oxygen/xonar_pcm179x.c:463:1-17: WARNING: Assignment of 0/1 to
bool variable
sound/pci/oxygen/xonar_pcm179x.c:505:1-17: WARNING: Assignment of 0/1 to
bool variable

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200422071646.48436-1-yanaijie@huawei.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>