clk: rockchip: rk3399: Add dummy support for ACLK_VDU clock

rk3399.dtsi from linux v5.19 and newer try to set VDU clock rate to
400 MHz using an assigned-clock-rates prop of the CRU node.

U-Boot does not use or need this clock so add dummy support for getting
and setting ACLK_VDU clock rate to allow CRU driver to be loaded with an
updated rk3399.dtsi.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
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 f0ce540..5934771 100644
--- a/drivers/clk/rockchip/clk_rk3399.c
+++ b/drivers/clk/rockchip/clk_rk3399.c
@@ -971,6 +971,7 @@
 	case ACLK_HDCP:
 	case ACLK_GIC_PRE:
 	case PCLK_DDR:
+	case ACLK_VDU:
 		break;
 	case PCLK_ALIVE:
 	case PCLK_WDT:
@@ -1061,6 +1062,7 @@
 	case ACLK_HDCP:
 	case ACLK_GIC_PRE:
 	case PCLK_DDR:
+	case ACLK_VDU:
 		return 0;
 	default:
 		log_debug("Unknown clock %lu\n", clk->id);