brcm63xx: Neufbox 6: fix switch by probing through DT

Probe the switch through DT instead of a platform device. This fixes
probe, as GPIO offsets are now properly accounted for.

Fixes the following issue:

[    0.802953] 8021q: 802.1Q VLAN Support v1.8
[    0.810518] rtl8366_smi: gpio_request failed for 18, err=-517

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

target/linux/brcm63xx/dts/nb6-ser-r0.dts

@@ -40,4 +40,12 @@
 			linux,code = <KEY_WPS_BUTTON>;
 		};
 	};
+
+	switch {
+		compatible = "realtek,rtl8367";
+		gpio-sda = <&gpio0 18 0>;
+		gpio-sck = <&gpio0 20 0>;
+
+		realtek,extif0 = <1 5 1 1 1 1 1 1 2>;
+	};
 };