soc.h has snd_soc_dapm_mutex_lock/unlock() definition and
many drivers are using it, but soc-dapm.c is not.

1st reason is snd_soc_dapm_mutex_lock/unlock() requests
snd_soc_dapm_context pointer as parameter (A), but sometimes soc-dapm.c
needs to use snd_soc_card (B).

(A)	static inline void snd_soc_dapm_mutex_lock(struct snd_soc_dapm_context *dapm)
	{
		mutex_lock_nested(&dapm->card->dapm_mutex, SND_SOC_DAPM_CLASS_RUNTIME);
	}			   ^^^^^^^^^^

(B)	mutex_lock_nested(&card->dapm_mutex, SND_SOC_DAPM_CLASS_RUNTIME);
			   ^^^^

2nd reason is it want to use SND_SOC_DAPM_CLASS_INIT for mutex_lock_nested(),
but helper is using _RUNTIME (A).

The conclusion is we want to use "dapm vs card" and "_RUNTIME vs _INIT"
for dapm lock/unlock. To enable this selfish request, this patch uses
_Generic macro. We can use snd_soc_dapm_mutex_lock/unlock() for both
dapm and card case.

	snd_soc_dapm_mutex_lock(dapm);	snd_soc_dapm_mutex_unlock(dapm);
	snd_soc_dapm_mutex_lock(card);	snd_soc_dapm_mutex_unlock(card);

Current soc-dapm.c is using both mutex_lock() and mutex_lock_nested().
This patch handles mutex_lock() as mutex_lock_nested(..., 0),
in other words, handles below as same.

	mutex_lock(&card->dapm_mutex);
	mutex_lock_nested(&card->dapm_mutex, SND_SOC_DAPM_CLASS_INIT);

Because people might misunderstand that _init() is mutex initialization,
this patch renames _INIT to _ROOT and adds new
snd_soc_dapm_mutex_lock_root() for it.

This patch also moves snd_soc_dapm_subclass definition from soc-dapm.h
to soc.h to keep related code together.

Because very complex soc.h vs soc-dapm.h relationship,
it is difficult/impossible to define these helper into soc-dapm.h.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87cz4hx3v0.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>