ARM: dts: msm: update micbias regulator in msmfalcon

Power regulator pm2falcon_bob is used to supply micbias
to WCD codec. Add the supply in codec supplies list.
As external buck supply is from VPH_PWR, remove
entries of s4 rail.

Change-Id: I24791396fff9bf612985ff2073e2a74356570a35
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>