Add set_channel_acquisition_mode to mock

pulse_lib/tests/mock_m3102a.py

@@ -28,6 +28,9 @@ class MockM3102A(Instrument):
         for prop in self.measure._ch_properties.values():
             prop.acquisition_mode = mode
 
+    def set_channel_acquisition_mode(self, ch_num, mode):
+        self.measure._ch_properties[ch_num].acquisition_mode = mode
+
     def get_channel_acquisition_mode(self, ch_num):
         return self.measure._ch_properties[ch_num].acquisition_mode