remove 'maxage' argument for read_* methods

'maxage' is not really used at any place. remove it, as this makes
the code cleaner

Change-Id: I6f10b4ab91fc57640336db1832716ca9012eb241
Reviewed-on: https://forge.frm2.tum.de/review/20347
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/metaclass.py

@@ -140,11 +140,11 @@ class ModuleMeta(type):
                     break
                 rfunc = getattr(base, 'read_' + pname, None)
 
-            def wrapped_rfunc(self, maxage=0, pname=pname, rfunc=rfunc):
+            def wrapped_rfunc(self, pname=pname, rfunc=rfunc):
                 if rfunc:
                     self.log.debug("rfunc(%s): call %r" % (pname, rfunc))
                     try:
-                        value = rfunc(self, maxage)
+                        value = rfunc(self)
                     except Exception as e:
                         pobj = self.accessibles[pname]
                         self.DISPATCHER.announce_update_error(self, pname, pobj, e)