arm64: dts: rockchip: Lower sd speed on quartz64-b

The previously stated speed of sdr-104 is too high for the hardware
to reliably communicate with some fast SD cards.

Lower this to sd-uhs-sdr50 to fix this.

Fixes: dcc8c66b ("arm64: dts: rockchip: add Pine64 Quartz64-B device tree")
Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Link: https://lore.kernel.org/r/20220721044307.48641-1-frattaroli.nicolas@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts

@@ -506,7 +506,7 @@ &sdmmc0 {
 	disable-wp;
 	pinctrl-names = "default";
 	pinctrl-0 = <&sdmmc0_bus4 &sdmmc0_clk &sdmmc0_cmd &sdmmc0_det>;
-	sd-uhs-sdr104;
+	sd-uhs-sdr50;
 	vmmc-supply = <&vcc3v3_sd>;
 	vqmmc-supply = <&vccio_sd>;
 	status = "okay";