staging: bcm2835-audio: unify FOURCC command definitions

The device communicates with the audio core using FOURCC codes. The
driver was generating them using different macros/expressions. We now
use the same macro to create them and centralize all the definitions.

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>