staging: bcm2835-audio: don't initialize memory twice

The memory is being allocated with devres_alloc(), wich ultimately uses
__GFP_ZERO to call kmalloc. We don't need to zero the memory area again
in bcm2835-audio.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>