power_supply: change getting and setting power supply properties

Replace all call sites which invoke the get/set_property apis on the
power_supply object with power_supply_get/set_property() api call.

Change-Id: Ibd4c5db6a50734f827878589df1f3e48a0062a06
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>