microblaze: Remove incorrect file path

Trivial.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/boot/dts/Makefile

@@ -1,6 +1,4 @@
 #
-# arch/microblaze/boot/Makefile
-#
 
 obj-y += linked_dtb.o