Set max fat to 60%

Min water + min muscle is 40%, so 60% seems like a better max for
fat. Also, it gives a nicer gauge view.

android_app/app/src/main/java/com/health/openscale/gui/views/FatMeasurementView.java

@@ -77,7 +77,7 @@ public class FatMeasurementView extends MeasurementView {
 
     @Override
     public float getMaxValue() {
-        return 80;
+        return 60;
     }
 
 }