clk: samsung: Add support for setting registers state before suspend

Some registers of clock controller have to be set to certain values before
entering system suspend state. Till now drivers did that on their own,
but it will be easier to handle it by generic code and let drivers simply
to provide the list of registers and their state.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sylwester Nawrocki <snawrocki@kernel.org>