clk: rockchip: Add 1.6GHz PLL rate for rk3399

We need this rate to generate 100, 200, and 228.57MHz from the same
PLL. 228.57MHz is useful for a pixel clock when the VPLL is used for
an external display.

Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>