armbian: remove adc-keys from RK3576 U-Boot device tree

SARADC channel 1 is susceptible to electrical interference when a USB
device is connected to the OTG port, causing rockchip_dnl_key_pressed()
to return true and U-Boot to enter download/recovery mode instead of
normal boot. The reComputer board has no physical volume-up button; this
node was inherited from the reference design and is not needed.

Author: mingzhangqun

patch/u-boot/legacy/u-boot-radxa-rk35xx/dt/rk3576-recomputer-rk3576-devkit.dts

@@ -13,21 +13,14 @@
 	model = "reComputer RK3576 DevKit";
 	compatible = "seeed,recomputer-rk3576-devkit", "rockchip,rk3576";
 
-	adc-keys {
-		compatible = "adc-keys";
-		io-channels = <&saradc 1>;
-		io-channel-names = "buttons";
-		keyup-threshold-microvolt = <1800000>;
-		u-boot,dm-pre-reloc;
-		status = "okay";
-
-		volumeup-key {
-			u-boot,dm-pre-reloc;
-			linux,code = <KEY_VOLUMEUP>;
-			label = "volume up";
-			press-threshold-microvolt = <1750000>;
-		};
-	};
+	/*
+	 * adc-keys removed: SARADC channel 1 is susceptible to electrical
+	 * interference when a USB device is connected to the OTG port, causing
+	 * rockchip_dnl_key_pressed() to return true and U-Boot to enter
+	 * download/recovery mode instead of normal boot.
+	 * The reComputer board has no physical volume-up button; this node was
+	 * inherited from the reference design and is not needed.
+	 */
 
 	vcc3v3_pcie: vcc3v3-pcie {
 		u-boot,dm-pre-reloc;