soc: samsung: pm_domains: Convert to regular platform driver

soc: samsung: pm_domains: Convert to regular platform driver

When Exynos power domain driver was introduced, the only way to ensure
that power domains will be instantiated before the devices which belongs
to them was to initialize them early enough, before the devices are
instantiated in the system. This in turn required not to use any platform
device infrastructure at all, as there have been no way to ensure proper
probe order between devices.

This has been finally changed and upcomming patch "driver core: Set
fw_devlink=on by default" ensures that each device will be probbed only
when its resource providers are ready. This allows to convert Exynos
power domain driver to regular platform driver.

This is also required by the mentioned commit to enable probing any
device which belongs to the Exynos power domains, as otherwise the core
won't notice that the power domains are in fact available.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20210113110320.13149-1-m.szyprowski@samsung.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>