[ALSA] _snd_cmipci_uswitch_put doesn't set zero flags

Playing with spdif output on cmipci i've noticed the SPDO5V option does
not change appropriate bits the register.
The _snd_cmipci_uswitch_put checks the change in flags in wrong way.
If 'active' state of an option corresponds to a _zero_ bits in a hw
register then function fails. The SPDO5V is the sample.
In the most cases 'active' state of option is set through an non-zerio
bits in a register. This case works fine.
The fix attached.
Unfortunately i was unable to change spdif output voltage anyway.
Although the register changes right at least.
From: Timofei V. Bondarenko <tim@ipi.ac.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>