RTC6226: Configure Vdd with supplied load in NPM

Configure the Vdd regulator with supplied load
in NPM mode. Configure the Vdd regulator with 0
load in LPM mode.

Adding support for reading load value for Vdd regulator from
device tree. If this property is not present, no explicit vote
required for load.

CRs-Fixed: 2840599
Change-Id: Ic2f12d9f9ce3e6a9ba6b58888cc5c202a74d8cc3
Signed-off-by: himta ram <hram@codeaurora.org>