arm: dts: rockchip: Sync rk3288 dtsi from linux

This sync has changes required to use HDMI CEC pin in U-Boot.

Sync dts from linux v5.8-rc5 commit:
	"ARM: dts: rockchip: define the two possible rk3288 CEC pins"
	(sha1: 838980dd04e994bf81cf104fa01ae60802146b39)
Signed-off-by: NSuniel Mahesh <sunil@amarulasolutions.com>
Signed-off-by: NJagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang<kever.yang@rock-chips.com>

arch/arm/dts/rk3288.dtsi

@@ -1085,6 +1085,12 @@
 			#interrupt-cells = <2>;
 		};
 
+		hdmi {
+			hdmi_cec_c0: hdmi-cec-c0 {
+				rockchip,pins = <7 RK_PC0 2 &pcfg_pull_none>;
+			};
+		};
+
 		pcfg_pull_up: pcfg-pull-up {
 			bias-pull-up;
 		};