gcc-7 warns about debug statements being left out here:
drivers/staging/bcm2835-audio/bcm2835-vchiq.c: In function 'bcm2835_audio_set_ctls':
drivers/staging/bcm2835-audio/bcm2835-vchiq.c:572:54: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
It's better to use no_printk(), which has the added advantage of checking
the format strings.