PM: schedule /sys/devices/.../power/state for removal

This lists the /sys/devices/.../power/state file, and its internal support,
as due for removal next year.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>