rfkill: print events when input handler is disabled/enabled

It is useful for debugging when we know if something disabled
the in-kernel rfkill input handler.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>