Using the power supply APIs requires selecting the appropriate
Kconfig symbol, otherwise we get this build failure:
drivers/hid/hid-steam.o: In function `steam_unregister':
hid-steam.c:(.text+0x1cc): undefined reference to `power_supply_unregister'
drivers/hid/hid-steam.o: In function `steam_battery_get_property':
hid-steam.c:(.text+0x2d2): undefined reference to `power_supply_get_drvdata'
drivers/hid/hid-steam.o: In function `steam_raw_event':
hid-steam.c:(.text+0xcba): undefined reference to `power_supply_changed'
drivers/hid/hid-steam.o: In function `steam_register':
hid-steam.c:(.text+0x13e3): undefined reference to `power_supply_register'
hid-steam.c:(.text+0x13fe): undefined reference to `power_supply_powers'