ad7172: impl default for ch_calibration

src/thermostat/ad7172/adc.rs

@@ -274,6 +274,16 @@ pub struct ChannelCalibration {
     bipolar: bool,
 }
 
+impl Default for ChannelCalibration {
+    fn default() -> Self {
+        ChannelCalibration {
+            offset: 0,
+            gain: 0,
+            bipolar: false,
+        }
+    }
+}
+
 impl ChannelCalibration {
     pub fn convert_data(&self, data: u32) -> ElectricPotential {
         let data = if self.bipolar {