Renesas is the only user of ak4613 on upstream for now, and
commit f28dbaa9 ("ASoC: ak4613: add TDM256 support")
added TDM256 support. Renesas tested part of it, because of
board connection.

It was assuming ak4613 is probed via Audio-Graph-Card, but it
might be probed via Simple-Audio-Card either.
It will indicates WARNING in such case. This patch fixup it.
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87h74v29f7.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>