power: supply: core: simplify charge_behaviour formatting

The function power_supply_show_charge_behaviour() is not needed and can
be removed completely.
Removing the function also saves a spurious read of the property from
the driver on each call.

The convulted logic was a leftover from an earlier patch revision.
Some restructuring made this cleanup possible.

Suggested-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/all/9e035ae4-cb07-4f84-8336-1a0050855bea@redhat.com/


Fixes: 4e61f1e9 ("power: supply: core: fix charge_behaviour formatting")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240329-power-supply-simplify-v1-1-416f1002739f@weissschuh.net


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