power_supply: Use of-thermal cdev registration API

With thermal frameworks of-thermal interface, thermal zone parameters can
be defined in devicetree. This includes cooling device mitigation levels
for a thermal zone. To take advantage of this, cooling device should use
the thermal_of_cooling_device_register API to register a cooling device.

Use thermal_of_cooling_device_register API to register the power supply
cooling device. This enables power supply cooling device be included in the
thermal zone parameter in devicetree.

Change-Id: I27d6043cf1d3121d97f8300bb89635204ae32955
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>