dtc: Bump version to v1.4.7

We've accumulated a bunch of bugfixes, including considerable improvements
to libfdt's memory safety, so get ready for another release.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/Makefile b/Makefile
index 6d55e13..d8ebc4f 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@
 #
 VERSION = 1
 PATCHLEVEL = 4
-SUBLEVEL = 6
+SUBLEVEL = 7
 EXTRAVERSION =
 LOCAL_VERSION =
 CONFIG_LOCALVERSION =