ALSA: snd-usb-caiaq: Remove duplicate A8DJ control

Remove a duplicate control which causes an error when it is registered,
and causes later controls to not be registered. The device does not have
a fourth ground lift control.

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