ASoC: soc-core: fixup references at soc_cleanup_card_resources()

ASoC: soc-core: fixup references at soc_cleanup_card_resources()

commit 53e947a0e1f7 ("ASoC: soc-core: merge card resources cleanup
method") merged cleanup method of snd_soc_instantiate_card() and
soc_cleanup_card_resources().

But, after this commit, if user uses unbind/bind to Component factor
drivers, Kernel might indicates refcount error at
soc_cleanup_card_resources().

The 1st reason is card->snd_card is still exist even though
snd_card_free() was called, but it is already cleaned.
We need to set NULL to it.

2nd is card->dapm and card create debugfs, but its dentry is still
exist even though it was removed. We need to set NULL to it.

Fixes: 53e947a0e1f7 ("ASoC: soc-core: merge card resources cleanup method")
Cc: stable@vger.kernel.org # for v5.1
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>