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

This reverts commit 645c08f1
which was reported to break the build a program using this header.

The original issue was addressed in the alsa-lib side recently, so we
can make the header more self-contained again.
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Fixes: 645c08f1 ("ALSA: uapi: Drop asound.h inclusion from asoc.h")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200331090023.8112-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/asoc.h

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