ASoC: soc-core: add lockdep_assert_held() at snd_soc_unregister_dai()

snd_soc_register_dai() has lockdep_assert_held() (A), but
snd_soc_unregister_dai() doesn't have lockdep_assert_held() (B).

void snd_soc_unregister_dai(...)
{
(B) dev_dbg(...);
list_del(...);
}

struct snd_soc_dai *snd_soc_register_dai(...)
{
...
(A) lockdep_assert_held(&client_mutex);
...
}

Both functions should be called with client_mutex lock.
Add missing lockdep_assert_held() at snd_soc_unregister_dai().

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/87jyx21nu4.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>