ASoC: soc-dapm.c: replace snd_soc_dapm_wcache to snd_soc_dapm_widget

Current ASoC has snd_soc_dapm_wcache, but its member is only
snd_soc_dapm_widget.

	struct snd_soc_dapm_wcache {
		struct snd_soc_dapm_widget *widget;
	};

It is no meaning for now, and makes code unreadable.
This patch replace snd_soc_dapm_wcache to snd_soc_dapm_widget directly.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/871qr6qayt.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>