arm64: dts: rockchip: Add pinmuxing for eMMC on QNAP TS433

Until now the emmc worked when booting because the bootrom set up the
pin config correctly to load the initial bootloader from it.

So when the kernel started it "just" reused this setup but never made
sure it was actually correct.

This then breaks when the system is started via some other means, like
downloading the initial bootloader via the bootrom usb download.

With actual emmc pin-config added, barebox is able to access the eMMC
even when booted via USB.

Fixes: 9da1c0327d ("arm64: dts: rockchip: Add basic support for QNAP TS-433")
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
[refined commit message to explain that we're currently just running
 on bootom-goodwill]
Link: https://lore.kernel.org/r/20250319113138.125192-2-uwe@kleine-koenig.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3568-qnap-ts433.dts

@@ -619,6 +619,8 @@ &sdhci {
 	bus-width = <8>;
 	max-frequency = <200000000>;
 	non-removable;
+	pinctrl-names = "default";
+	pinctrl-0 = <&emmc_bus8 &emmc_clk &emmc_cmd &emmc_datastrobe>;
 	status = "okay";
 };