ASoC: fsl: imx-audmix: remove dummy dai_link->platform

Dummy dai_link->platform is not needed.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Tested-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/877cu6f619.wl-kuninori.morimoto.gx@renesas.com


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