fix maps crash when no CP is set

The check in the maps code for whether a CP is set was backwards, causing
a segfault on the subsequent call to Zones::getCP().  To reproduce, create
a new cyclist and import a ride with lat/lng data.  The import succeeds, but
GC crashes when you click "Save" and on all subsequent restarts.

src/GoogleMapControl.cpp

@@ -255,7 +255,7 @@ string GoogleMapControl::CreatePolyLine(RideItem *ride)
     int cp;
     int intervalTime = 30;  // 30 seconds
     int zone =ride->zoneRange();
-    if(zone >= 0)
+    if(zone < 0)
     {
         cp = 300;  // default cp to 300 watts
     }