ALSA: usb-audio: Add custom mixer status quirks for RME CC devices

Adds several vendor specific mixer quirks for RME's Class Compliant
USB devices. These provide extra status information from the device
otherwise not available.

These include AES/SPDIF rate and status information, current system
sampling rate and measured frequency. This information is especially
useful in cases where device's clock is slaved to external clock
source.
Signed-off-by: Jussi Laako <jussi@sonarnerd.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>