ASoC: rsnd: fixup MIX kctrl registration

Renesas sound device has many IPs and many situations.
If platform/board uses MIXer, situation will be more complex.
To avoid duplicate DVC kctrl registration when MIXer was used,
it had original flags.
But it was issue when sound card was re-binded, because
no one can't cleanup this flags then.

To solve this issue, commit 9c698e84 ("ASoC: rsnd: tidyup
registering method for rsnd_kctrl_new()") checks registered
card->controls, because if card was re-binded, these were cleanuped
automatically. This patch could solve re-binding issue.
But, it start to avoid MIX kctrl.

To solve these issues, we need below.
To avoid card re-binding issue: check registered card->controls
To avoid duplicate DVC registration: check registered rsnd_kctrl_cfg
To allow multiple MIX registration: check registered rsnd_kctrl_cfg
This patch do it.

Fixes: 9c698e84

 ("ASoC: rsnd: tidyup registering method for rsnd_kctrl_new()")
Reported-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-By: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>