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

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

This reverts commit 254ca2b911a5efabf9b2e992108b88d12ae50bca
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: 254ca2b911a5 ("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.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>