PM: domains: Add helper functions to attach/detach multiple PM domains

Attaching/detaching of a device to multiple PM domains has started to
become a common operation for many drivers, typically during ->probe() and
->remove(). In most cases, this has lead to lots of boilerplate code in the
drivers.

To fixup up the situation, let's introduce a pair of helper functions,
dev_pm_domain_attach|detach_list(), that driver can use instead of the
open-coding. Note that, it seems reasonable to limit the support for these
helpers to DT based platforms, at it's the only valid use case for now.

Suggested-by: Daniel Baluta <daniel.baluta@nxp.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20240130123951.236243-2-ulf.hansson@linaro.org