clk: rockchip: add mipidsi clock on rk3288

sclk_mipidsi_24m is the gating of mipi dsi phy.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>