power: supply: core: constify psy_tzd_ops

This struct is never modified, so mark it const.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20240828-power-supply-const-psy_tzd_ops-v1-1-dc27176fda5b@weissschuh.net


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