base/platform: assert that dev_pm_domain callbacks are called unconditionally

When a platform driver doesn't provide a .remove callback the function
platform_drv_remove isn't called and so the call to dev_pm_domain_attach
called at probe time isn't paired by dev_pm_domain_detach at remove
time.

To fix this (and similar issues if different callbacks are missing) hook
up the driver callbacks unconditionally and make them aware that the
platform callbacks might be missing.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>