power: supply: core: Remove unused power_supply_set_battery_charged

power_supply_set_battery_charged() has been unused since 2019's
commit 0f884f8a ("ARM: pxa: remove raumfeld board files and
defconfig")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20250307230225.128775-2-linux@treblig.org


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>