power: supply: core: ease special formatting implementations

By moving the conditional into the default-branch of the switch new
additions to the switch won't have to bypass the conditional.

This makes it easier to implement those special cases like the upcoming
change to the formatting of "charge_behaviour".

Suggested-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/lkml/53082075-852f-4698-b354-ed30e7fd2683@redhat.com/


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20240303-power_supply-charge_behaviour_prop-v2-2-8ebb0a7c2409@weissschuh.net


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