staging: bcm2835-audio: Clean up include files in bcm2835-ctl.c

Only a few of them are really needed.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>