HID: nvidia-shield: Add battery support for Thunderstrike

Use power supply API to expose battery information about connected
Thunderstrike controllers to the system. Provide information on battery
capacity, charge status, charger type, voltage, and temperature.
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>