MAINTAINERS: FLATTENED DEVICE TREE: correct maintained path

Change due to commit b08c8c48 ("libfdt: move headers to
<linux/libfdt.h> and <linux/libfdt_env.h>")

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

MAINTAINERS

@@ -306,7 +306,7 @@ T:	git git://git.denx.de/u-boot-fdt.git
 F:	lib/fdtdec*
 F:	lib/libfdt/
 F:	include/fdt*
-F:	include/libfdt*
+F:	include/linux/libfdt*
 F:	cmd/fdt.c
 F:	common/fdt_support.c