fix initwrite behaviour

with handlers, a parameter from the cfg file which is not the
first of parameters with the same handler were not written.
fix: write_<param> method is called for all parameters in
<module>.writeDict even if there is no poll entry.

with this fix, when a parameter has the property initwrite=True,
the write_<param> method is called even when <param>
is not polled and even when <module>.pollerClass is None

Change-Id: I9b397deb5b20709fc4fa7c860c85b251a204c7f6

test/test_poller.py

@@ -163,7 +163,8 @@ class Module:
     def pollOneParam(self, pname):
         getattr(self, 'read_' + pname)()
 
-    writeOrPoll = pollOneParam
+    def writeInitParams(self):
+        pass
 
     def __repr__(self):
         rdict = self.__dict__.copy()