power: supply: axp288_fuel_gauge: Use devm_power_supply_register()

Use devm_power_supply_register() instead of
power_supply_register().

Note as a side-effect this changes the release order so that now
first the IRQs get free-ed and then the psy gets unregistered.
This is actually a bug-fix since this fixes the IRQ possibly trying
to reference the unregistered psy.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>