staging: greybus: audio_codec.c: space required before the open brace

Minor error spotted by checkpatch.pl in greybus
space required before the open brace '{'

Signed-off-by: Richard Groux <rgroux@sauron-mordor.net>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>