Documentation/devicetree: mpc5200.txt: fix pointer to location of fsl,mpc5200-mscan node

This patch fixes the pointer to the location of the fsl,mpc5200-mscan
device tree node binding documentation.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt

@@ -195,4 +195,4 @@ External interrupts:
 
 fsl,mpc5200-mscan nodes
 -----------------------
-See file can.txt in this directory.
+See file Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt