clk: rockchip: rk356x: Add CLK_USB3OTGx_REF support

The CLK_USB3OTGx_REF clocks is used as reference clock for USB3 block.

Add simple support to get rate of CLK_USB3OTGx_REF clocks to fix
reference clock period configuration.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Acked-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/clk/rockchip/clk_rk3568.c b/drivers/clk/rockchip/clk_rk3568.c
index 57ef27d..999f48e 100644
--- a/drivers/clk/rockchip/clk_rk3568.c
+++ b/drivers/clk/rockchip/clk_rk3568.c
@@ -2417,6 +2417,8 @@
 	case BCLK_EMMC:
 		rate = rk3568_emmc_get_bclk(priv);
 		break;
+	case CLK_USB3OTG0_REF:
+	case CLK_USB3OTG1_REF:
 	case TCLK_EMMC:
 		rate = OSC_HZ;
 		break;
@@ -2596,6 +2598,8 @@
 	case BCLK_EMMC:
 		ret = rk3568_emmc_set_bclk(priv, rate);
 		break;
+	case CLK_USB3OTG0_REF:
+	case CLK_USB3OTG1_REF:
 	case TCLK_EMMC:
 		ret = OSC_HZ;
 		break;