ASoC: audio-graph-card2-custom-sample.dtsi: use card->name to avoid long name

Current Card2 Custom Sample will be too long Card name, and be error

	audio-graph-card2-custom-sample audio-graph-card2-custom-sample \
		ASoC: driver name too long \
		audio-graph-card2-custom-sample' -> 'audio-graph-car'

This patch uses short name to avoid it

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87bkke7qzf.wl-kuninori.morimoto.gx@renesas.com


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