clk: samsung: Provide common helpers for register save/restore

As suspend/resume handlers are being moved to SoC specific code, due to
differencies in suspend/resume handling of particular SoCs, to minimize
code duplication this patch provides common register save/restore
helpers that save/restore given list of registers of clock controller.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Thomas Abraham <thomas.ab@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>