genlib/io.py: fix copy/paste error (thanks rjo)

enjoy-digital · enjoy-digital · commit bf28664cb470 · 2015-03-12T18:49:49.000+01:00
diff --git a/migen/genlib/io.py b/migen/genlib/io.py
@@ -16,4 +16,4 @@ def iter_expressions(self):
 
 	@staticmethod
 	def lower(dr):
-		raise NotImplementedError("Attempted to use a reset synchronizer, but platform does not support them")
+		raise NotImplementedError("Attempted to use a differential input, but platform does not support them")
