Bugfix for CHECK_HAVE_WARN_PHANDLE()

At present, the tree checking code in dtc will die with an assertion
failure if given a tree which has the invalid value 0 or -1 in a
property which should contain a phandle.  This patch fixes the check
to die more gracefully with an error message indicating the invalid
phandle value.

Signed-off-by: David Gibson <dwg@au1.ibm.com>

livetree.c

@@ -427,10 +427,15 @@ static int check_structure(struct node *tree)
 		struct node *ref; \
 		CHECK_HAVE_WARN_ONECELL((xnode), (propname)); \
 		if (prop) {\
+			cell_t phandle = propval_cell(prop); \
+			if ((phandle == 0) || (phandle == -1)) { \
+				DO_ERR("\"%s\" property in %s contains an invalid phandle %x\n", (propname), (xnode)->fullpath, phandle); \
+			} else { \
 				ref = get_node_by_phandle((root), propval_cell(prop)); \
 				if (! ref) \
 					DO_ERR("\"%s\" property in %s refers to non-existant phandle %x\n", (propname), (xnode)->fullpath, propval_cell(prop)); \
 			} \
+		} \
 	} while (0)
 
 #define CHECK_HAVE_WARN_STRING(node, propname) \