staging: bcm2835-audio: remove function snd_bcm2835_new_ctl()

The function snd_bcm2835_new_ctl() is declared but not defined.
Its definition was removed 1 year ago in the
commit 143b67f1 ("staging: bcm2835-audio: remove compat ALSA card")
Signed-off-by: Calvince Otieno <calvncce@gmail.com>
Link: https://lore.kernel.org/r/ZTDap2d5X7eXXPo2@lab-ubuntuSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/bcm2835-audio/bcm2835.h

@@ -84,7 +84,6 @@ struct bcm2835_alsa_stream {
 	int idx;
 };
 
-int snd_bcm2835_new_ctl(struct bcm2835_chip *chip);
 int snd_bcm2835_new_pcm(struct bcm2835_chip *chip, const char *name,
 			int idx, enum snd_bcm2835_route route,
 			u32 numchannels, bool spdif);