ARM: dts: imx6q: add missing links between ipu2 and mipi dsi

The backlinks are already there since commit 4520e692 ("ARM: dts:
imx6qdl: Add IPU DI ports and endpoints, move imx-drm node to dtsi")
and were moved by commit 70c2652c ("ARM: dts: imx6qdl: Move existing
MIPI DSI ports into a new 'ports' node"), but the links from IPU2 DI0/1
to the MIPI DSI mux are missing. Fix this.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6q.dtsi

@@ -162,6 +162,7 @@ ipu2_di0_hdmi: endpoint@1 {
 				};
 
 				ipu2_di0_mipi: endpoint@2 {
+					remote-endpoint = <&mipi_mux_2>;
 				};
 
 				ipu2_di0_lvds0: endpoint@3 {
@@ -183,6 +184,7 @@ ipu2_di1_hdmi: endpoint@1 {
 				};
 
 				ipu2_di1_mipi: endpoint@2 {
+					remote-endpoint = <&mipi_mux_3>;
 				};
 
 				ipu2_di1_lvds0: endpoint@3 {