clk: rockchip: rk3399: Set 50MHz ddr clock

Add support for setting 50MHz ddr clock.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: YouMin Chen <cym@rock-chips.com>
Reviewed-by: Kever Yang <Kever.yang@rock-chips.com>
diff --git a/drivers/clk/rockchip/clk_rk3399.c b/drivers/clk/rockchip/clk_rk3399.c
index 69a887f..2c00166 100644
--- a/drivers/clk/rockchip/clk_rk3399.c
+++ b/drivers/clk/rockchip/clk_rk3399.c
@@ -827,6 +827,10 @@
 
 	/*  clk_ddrc == DPLL = 24MHz / refdiv * fbdiv / postdiv1 / postdiv2 */
 	switch (set_rate) {
+	case 50 * MHz:
+		dpll_cfg = (struct pll_div)
+		{.refdiv = 1, .fbdiv = 12, .postdiv1 = 3, .postdiv2 = 2};
+		break;
 	case 200 * MHz:
 		dpll_cfg = (struct pll_div)
 		{.refdiv = 1, .fbdiv = 50, .postdiv1 = 6, .postdiv2 = 1};