ALSA: snd-usb-caiaq: Send the correct command when setting controls

Fixes a bug where an incorrect command was sent which had no effect on the
device.

Signed-off-by: Mark Hills <mark@pogo.org.uk>
Acked-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>