riscv: dts: starfive: add assigned-clock* to limit frquency

In JH7110 SoC, we need to go by-pass mode, so we need add the
assigned-clock* properties to limit clock frquency.
Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

arch/riscv/boot/dts/starfive/jh7110-starfive-visionfive-2.dtsi

@@ -250,6 +250,8 @@ &i2stx1 {
 
 &mmc0 {
 	max-frequency = <100000000>;
+	assigned-clocks = <&syscrg JH7110_SYSCLK_SDIO0_SDCARD>;
+	assigned-clock-rates = <50000000>;
 	bus-width = <8>;
 	cap-mmc-highspeed;
 	mmc-ddr-1_8v;
@@ -266,6 +268,8 @@ &mmc0 {
 
 &mmc1 {
 	max-frequency = <100000000>;
+	assigned-clocks = <&syscrg JH7110_SYSCLK_SDIO1_SDCARD>;
+	assigned-clock-rates = <50000000>;
 	bus-width = <4>;
 	no-sdio;
 	no-mmc;