ASoC: export DPCM runtime update functions

This makes DPCM runtime update functions available for external
calling. As an example, virtualised ASoC component drivers may need
to call these when managing shared DAPM routes that are used by more
than one driver (i.e. when host driver and guest drivers have a DAPM
path from guest PCM to host DAI where some parts are owned by host
driver and others by guest driver).

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20200312095214.15126-3-guennadi.liakhovetski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>