ARM: dts: msm: Add Battery voltage ADC line for APQ8084

Add the Vph ADC line for battery voltage monitoring.
Add configuration to do periodic reads on the ADC line.
Remove the redundant mpp6_div1 ADC line definition.

CRs-Fixed: 629894
Change-Id: Iced3d8fdbe05092d6b6bc6dbf8a0178387dfa440
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>