Add mixer quirk for Tascam US-16x08 usb interface.
Even that this is an usb compliant device,
the input channels and DSP functions (EQ/Compressor) aren't accessible
by default.
Signed-off-by: NDetlef Urban <onkel@paraair.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>