Remove leading underscores from identifiers

In a number of places, dtc and associated tools and test code use
leading _ characters on identifiers to flag them as "internal", an
idiom taken from the Linux kernel.  This is a bad idea in a userspace
program, because identifiers with a leading _ are reserved for the C
library / system.

In some cases, the extra _ served no real purpose, so simply drop it.  In
others move to the end of the identifier, which is a convention we're free
to use for our own purposes.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

dtc.h

@@ -1,5 +1,5 @@
-#ifndef _DTC_H
-#define _DTC_H
+#ifndef DTC_H
+#define DTC_H
 
 /*
  * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.
@@ -289,4 +289,4 @@ struct dt_info *dt_from_source(const char *f);
 
 struct dt_info *dt_from_fs(const char *dirname);
 
-#endif /* _DTC_H */
+#endif /* DTC_H */