ARM: dts: mdm9640: Enable antenna sharing

QCA6174 board on msmzirc platform uses antenna sharing. Enable it
by enabling the required LDOs without which 2.4G band TX power
are lower than expected.

CRs-fixed: 754944
Change-Id: Ic2c60099ac6dd30b9da56a1c432dd3233a9c7876
Signed-off-by: Prashanth Bhatta <bhattap@codeaurora.org>