ASoC: Intel: Skylake: Fix DMA position reporting for capture stream

As per hardware recommendation, for every capture stream completion
following operations need to be done in order to reflect the actual
data that is received in position buffer.

1. Wait for 20us before reading the DMA position in buffer once the
interrupt is generated for stream completion.
2. Read any of the register to flush the DMA position value. This is
dummy read operation.

Signed-off-by: Dharageswari R <dharageswari.r@intel.com>
Signed-off-by: Hardik T Shah <hardik.t.shah@intel.com>
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>