arm64: dts: stratix10: enable MMC highspeed support

Add 'cap-mmc-highspeed' property to enable high-speed support for MMC cards.
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>

arch/arm64/boot/dts/altera/socfpga_stratix10_socdk.dts

@@ -107,6 +107,7 @@ phy0: ethernet-phy@0 {
 &mmc {
 	status = "okay";
 	cap-sd-highspeed;
+	cap-mmc-highspeed;
 	broken-cd;
 	bus-width = <4>;
 };