ARM: dts: imx53: Fix LDB OF graph warning

Single child nodes in OF graph don't need an address and now dtc will
warn about this:

Warning (graph_child_address): /soc/aips@50000000/ldb@53fa8008/lvds-channel@0: graph node has single child node 'port@0', #address-cells/#size-cells are not necessary

Since the LDB should always have an output port, fix the warning by
adding the output port, 2, to the DT.

Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NRob Herring <robh@kernel.org>
Reviewed-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx53-ppd.dts

@@ -555,8 +555,6 @@
 		status = "okay";
 
 		port@2 {
-			reg = <2>;
-
 			lvds0_out: endpoint {
 				remote-endpoint = <&panel_in_lvds0>;
 			};

arch/arm/boot/dts/imx53.dtsi

@@ -485,6 +485,10 @@
 							remote-endpoint = <&ipu_di0_lvds0>;
 						};
 					};
+
+					port@2 {
+						reg = <2>;
+					};
 				};
 
 				lvds-channel@1 {
@@ -500,6 +504,10 @@
 							remote-endpoint = <&ipu_di1_lvds1>;
 						};
 					};
+
+					port@2 {
+						reg = <2>;
+					};
 				};
 			};