ASoC: wcd9xxx: Enable micbias always when headset is detected

As micbias is shared on 8x10, we cannot use vddio switch to
detect special headsets. We can keep micbias always on
to support these headsets.

Change-Id: Id62dfdf78bed2ea63e5fd8c6e6a8da2f19ee5f36
Signed-off-by: Simmi Pateriya <simmip@codeaurora.org>