ASoC: wm_adsp: Factor out ADSP2 boot proceedure

Move the ADSP2 boot proceedure into a work structure in preparation for
running it asynchronously with the reset of the audio path bring up.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/sound/soc/codecs/wm_adsp.h b/sound/soc/codecs/wm_adsp.h
index d018dea..b172c1d 100644
--- a/sound/soc/codecs/wm_adsp.h
+++ b/sound/soc/codecs/wm_adsp.h
@@ -59,6 +59,8 @@
 	struct regulator *dvfs;
 
 	struct list_head ctl_list;
+
+	struct work_struct boot_work;
 };
 
 #define WM_ADSP1(wname, num) \