ASoC: Fixup build error for mt6358

This patch fixup build error for
commit 6a8d4198 ("ASoC: mediatek: mt6358: add codec driver")

Fixes: commit 6a8d4198 ("ASoC: mediatek: mt6358: add codec driver")
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>