ASoC: Intel: Skylake: Add helper function to setup host/link dma

This patch adds helper function to configure the host/link DMA when
the DMA is in decoupled mode.
Next patch adds the usage of this helper routines for configuring
DMA in Mixer event handler.

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>