V4L/DVB (12345): em28xx: fix audio VIDIOC_S_CTRL adjustments on devices without ac97

Even devices without ac97 needs to call analog audio setup function, to
properly set xclk and mute/unmute.

Thanks to Angelo Cano <acano@fastmail.fm> for reporting and testing it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>