ASoC: sn95031: fix the DMIC path routing

This patch makes the DMIC dynamically connect to TX Mux, earlier code had
erroneously made this as static path

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Harsha Priya <priya.harsha@intel.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>