staging: bcm2835-audio: Use standard error print helpers

For making the whole code more consistent, replace the home-made debug
print macros with the standard dev_err() & co.

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>