include/dm.h: Remove duplicated include directive

Remove duplicated inclusion of dm/ofnode.h

Signed-off-by: Liviu Dudau <liviu.dudau@foss.arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
Drop period at end of commit subject:
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dm.h b/include/dm.h
index bf4b07d..2e1afda 100644
--- a/include/dm.h
+++ b/include/dm.h
@@ -6,7 +6,6 @@
 #ifndef _DM_H_
 #define _DM_H_
 
-#include <dm/ofnode.h>
 #include <dm/device.h>
 #include <dm/fdtaddr.h>
 #include <dm/ofnode.h>