ASoC: arizona: Propagate errors from arizona_spk_init

arizona_spk_init uses snd_soc_dapm_new_control which since
commit 37e1df8c

 ("ASoC: dapm: handle probe deferrals") will
occasionally request a probe deferral. Which means we should propagate the
error out of our driver from it.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>