clk: rockchip: Properly include clk.h

clk: rockchip: Properly include clk.h

Clock provider drivers generally shouldn't include clk.h because
it's the consumer API. Only include clk.h if it's actually used.

Cc: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>