ASoC: rt5645: add API to select ASRC clock source

This patch defines an API to select the clock source for specified filters.

Signed-off-by: Fang, Yang A <yang.a.fang@intel.com>
Acked-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>