Fix OSC's set_cvs declaration (#442)

Author: npossamai

software/contrib/osc_control.py

@@ -110,7 +110,7 @@ def set_cv(self, cv_out, data):
             cv_out.voltage(data.values[0] * europi_config.MAX_OUTPUT_VOLTAGE)
         self.ui_dirty = True
 
-    def set_cvs(data):
+    def set_cvs(self, data):
         """
         Set the level for all CVs