hw: Remove device_class_set_parent_reset()

hw: Remove device_class_set_parent_reset()

There are no callers of device_class_set_parent_reset() left in the tree,
as they've all been converted to use three-phase reset and the
corresponding resettable_class_set_parent_phases() function.
Remove device_class_set_parent_reset().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240830145812.1967042-5-peter.maydell@linaro.org