Fix custom marker updates on android react-native-maps#1611 react-nat…

…ive-maps#2048

Android:
[react-native-maps#2320](react-native-maps#2320)
Fixed custom marker updates on Android

lib/android/src/main/java/com/airbnb/android/react/maps/AirMapMarker.java

@@ -300,8 +300,10 @@ public void setImage(String uri) {
 
   public MarkerOptions getMarkerOptions() {
     if (markerOptions == null) {
-      markerOptions = createMarkerOptions();
+      markerOptions = new MarkerOptions(); 
     }
+
+    fillMarkerOptions(markerOptions);
     return markerOptions;
   }
 
@@ -355,8 +357,8 @@ private BitmapDescriptor getIcon() {
     }
   }
 
-  private MarkerOptions createMarkerOptions() {
-    MarkerOptions options = new MarkerOptions().position(position);
+  private MarkerOptions fillMarkerOptions(MarkerOptions options) {
+    options.position(position);
     if (anchorIsSet) options.anchor(anchorX, anchorY);
     if (calloutAnchorIsSet) options.infoWindowAnchor(calloutAnchorX, calloutAnchorY);
     options.title(title);