ASoC: rt5670: Remove struct rt5670_platform_data

platform_data is an obsolete concept, instead device_properties,
set through e.g. device-tree, should be used.

struct rt5670_platform_data is only used internally by the rt5670 codec
driver, so lets remove it before someone starts relying on it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200703100823.258033-2-hdegoede@redhat.com
Signed-off-by: Mark Brown <broonie@kernel.org>