ARM: dts: sun9i: cubieboard4: Remove card detect pull-up

The board has an external pull-up on the card-detect signal, so there's no
need to add another one.

This also removes a DTC warning.
Acked-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun9i-a80-cubieboard4.dts

@@ -85,7 +85,7 @@
 
 &mmc0 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&mmc0_pins>, <&mmc0_cd_pin_cubieboard4>;
+	pinctrl-0 = <&mmc0_pins>;
 	vmmc-supply = <&reg_dcdc1>;
 	bus-width = <4>;
 	cd-gpios = <&pio 7 18 GPIO_ACTIVE_HIGH>; /* PH18 */
@@ -128,14 +128,6 @@
 	clocks = <&ac100_rtc 0>;
 };
 
-&pio {
-	mmc0_cd_pin_cubieboard4: mmc0_cd_pin@0 {
-		pins = "PH18";
-		function = "gpio_in";
-		bias-pull-up;
-	};
-};
-
 &r_ir {
 	status = "okay";
 };