ALSA: uapi: Drop asound.h inclusion from asoc.h

The asound.h isn't always available while asoc.h itself is distributed
in alsa-lib package.  So we need to avoid the unnecessary inclusion of
asound.h from there.

Link: https://lore.kernel.org/r/20191220153415.2740-6-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/asoc.h

@@ -17,7 +17,6 @@
 #define __LINUX_UAPI_SND_ASOC_H
 
 #include <linux/types.h>
-#include <sound/asound.h>
 
 /*
  * Maximum number of channels topology kcontrol can represent.