power: supply: sysfs: Add power_supply_show_enum_with_available() helper

Turn power_supply_charge_behaviour_show() into a generic function for
showing enum values with their available (for writing) values shown
and the current value shown surrounded by sqaure-brackets like
the show() output for "usb_type" and "charge_behaviour".

This is a preparation patch for refactoring the "usb_type" property
handling to use a bitmask indicating available usb-types + this new
generic function.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240831142039.28830-5-hdegoede@redhat.com


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