PM / Domains: Add APIs to attach/detach a PM domain for a device

To maintain scalability let's add common methods to attach and detach
a PM domain for a device, dev_pm_domain_attach|detach().

Typically dev_pm_domain_attach() shall be invoked from subsystem level
code at the probe phase to try to attach a device to its PM domain.
The reversed actions may be done a the remove phase and then by
invoking dev_pm_domain_detach().

When attachment succeeds, the attach function should assign its
corresponding detach function to a new ->detach() callback added in the
struct dev_pm_domain.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>