riscv: dts: cv18xx: Drop unused dummy clocks

Introduced in commit 5a4e0625ac77 ("riscv: dts: sophgo: Add ethernet
node"), eth_{csrclk,ptpclk} were used as placeholders for ethernet
controller. As the real clock controller has been added, drop them to
clean the devicetree up.

Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/dts/cv18xx.dtsi b/arch/riscv/dts/cv18xx.dtsi
index 8a7386b..6fac247 100644
--- a/arch/riscv/dts/cv18xx.dtsi
+++ b/arch/riscv/dts/cv18xx.dtsi
@@ -46,20 +46,6 @@
 		#clock-cells = <0>;
 	};
 
-	eth_csrclk: eth-csrclk {
-		compatible = "fixed-clock";
-		clock-frequency = <250000000>;
-		clock-output-names = "eth_csrclk";
-		#clock-cells = <0x0>;
-	};
-
-	eth_ptpclk: eth-ptpclk {
-		compatible = "fixed-clock";
-		clock-frequency = <50000000>;
-		clock-output-names = "eth_ptpclk";
-		#clock-cells = <0x0>;
-	};
-
 	soc {
 		compatible = "simple-bus";
 		interrupt-parent = <&plic>;