dtc: Handle linux,phandle properties which self-reference

Currently, dtc will generate phandles for nodes which are referenced
elsewhere in the tree.  phandles can also be explicitly assigned by
defining the linux,phandle property.  However, there is no way,
currently to tell dtc to generate a phandle for a node if it is not
referenced elsewhere.  This is inconvenient when it's expected that
later processing on the flat tree might add nodes which _will_
the node in question.

One way one might attempt to do this is with the construct:
	mynode: mynode {
		linux,phandle = <&mynode>;
		/* ... */
	};
Though it's a trifle odd, there's really only one sensible meaning
which can be assigned to this construct: allocate a unique phandle to
"mynode" and put that in its linux,phandle property (as always).

Currently, however, dtc will choke on this self-reference.  This patch
corrects this, making the construct above give the expected results.
It also ensures a more meaningful error message is given if you
attempt to process the nonsensical construct:
	mynode: mynode {
		linux,phandle = <&someothernode>;
		/* ... */
	};

The 'references' testcase is extended to cover this case, as well.

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