clk: cs2000: add Suspend/Resume feature

CS2000 needs re-setup when redume, otherwise, it can't
handle correct clock rate.

Signed-off-by: Khiem Nguyen <khiem.nguyen.xt@rvc.renesas.com>
[Kuninori: cleanup original patch]
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>