power_supply: Register battery as a thermal zone

Battery and charger contribute to Thermals in most of the embedded
devices. So, it makes sense to identify them as Thermal zones in a
particular platform.

This patch registers a thermal zone if the power supply is reporting
a temperature property. The thermal zone will be used by platform's
thermal management solution.

Signed-off-by: Jenny TC <jenny.tc@intel.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>