ina219: fix shift value (#2577)

According to the datasheet, ADC gain bits are [11...12]

code/espurna/sensors/INA219Sensor.h

@@ -258,7 +258,7 @@ private:
             value |= (conf.bus_mode << 7) | (conf.shunt_mode << 3);
 
             value &= ~GainMask;
-            value |= (conf.gain << 12);
+            value |= (conf.gain << 11);
 
             value &= ~BusRangeMask;
             value |= (conf.bus_range << 13);