ALSA: Use standard device refcount for card accounting

Drop the own refcount but use the standard device refcounting via
get_device() and put_device().  Introduce a new completion to snd_card
instead of the wait queue for syncing the last release, which is used
in snd_card_free().

Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --cc include/sound/core.h
Simple merge

diff --cc sound/core/init.c
Simple merge

diff --cc sound/core/sound.c
Simple merge

diff --cc sound/core/sound_oss.c
Simple merge