arm/dt: msm8974: Configure whether micbias 2 is dedicated to headset

Configure micbias 2 sharing information through device tree so codec driver
can utilize this information for MBHC functionality.

The micbias 2 of msm8974 Liquid is shared by DMIC and headset mic.

CRs-Fixed: 470298
Change-Id: I642697e3a57f7be4cd5e707900e9680c98b821ef
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>