microblaze: Add missing FILE tag to MAINTAINERS

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/MAINTAINERS b/MAINTAINERS
index ca2997a..782ea4f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3680,6 +3680,7 @@
 W:	http://www.monstr.eu/fdt/
 T:	git git://git.monstr.eu/linux-2.6-microblaze.git
 S:	Supported
+F:	arch/microblaze/
 
 MICROTEK X6 SCANNER
 P:	Oliver Neukum