ASoC: sunxi: fix a sound binding broken reference

Address this rename:
	Documentation/devicetree/bindings/sound/{sun4i-i2s.txt -> allwinner,sun4i-a10-i2s.yaml}

Fixes: 0a0ca8e9 ("dt-bindings: sound: Convert Allwinner I2S binding to YAML")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Link: https://lore.kernel.org/r/9932608f32030c886d906ea656eda8408c544776.1564140865.git.mchehab+samsung@kernel.org


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