ALSA: vmaster: Fix the regression of missing vmaster hook call

The commit [1ca2f2ec: ALSA: vmaster: Add snd_ctl_sync_vmaster() helper
function] changed master_put() function and the check for the required
vmaster hook call is wrongly performed now, which results in the
missing hook call upon "Master Playback Switch" value changes.
This patch corrects the check logic.

Signed-off-by: Takashi Iwai <tiwai@suse.de>