arm64: dts: allwinner: a64: Fix the TCON output clock

Even though we shouldn't really have any external user of the clock
provided by the TCON, if clock-output-names is set, then #clock-cells must
be there as well.

Fix this.
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi

@@ -352,6 +352,7 @@ tcon0: lcd-controller@1c0c000 {
 			clocks = <&ccu CLK_BUS_TCON0>, <&ccu CLK_TCON0>;
 			clock-names = "ahb", "tcon-ch0";
 			clock-output-names = "tcon-pixel-clock";
+			#clock-cells = <0>;
 			resets = <&ccu RST_BUS_TCON0>, <&ccu RST_BUS_LVDS>;
 			reset-names = "lcd", "lvds";