ASoC: dapm: declare missing structure prototypes

To fix compilation warnings:

- struct 'snd_soc_pcm_runtime' declared inside parameter list will not
be visible outside of this definition or declaration
- struct 'soc_enum' declared inside parameter list will not be visible
outside of this definition or declaration

Declares the missing structure prototypes.

Signed-off-by: Tzung-Bi Shih <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/sound/soc-dapm.h

···
 #include <sound/asoc.h>
 
 struct device;
+struct snd_soc_pcm_runtime;
+struct soc_enum;
 
 /* widget has no PM register bit */
 #define SND_SOC_NOPM	-1