Plane: rely on conversion from long to int for DO_FOLLOW

we have code which tries to handle commands coming in as command long as command int.

Change to rely on that code working, rather than handling both command-long and command-int variants

ArduPlane/GCS_Mavlink.cpp

@@ -1102,16 +1102,6 @@ MAV_RESULT GCS_MAVLINK_Plane::handle_command_long_packet(const mavlink_command_l
         return MAV_RESULT_ACCEPTED;
 #endif
 
-#if AP_SCRIPTING_ENABLED
-    case MAV_CMD_DO_FOLLOW:
-        // param1: sysid of target to follow
-        if ((packet.param1 > 0) && (packet.param1 <= 255)) {
-            plane.g2.follow.set_target_sysid((uint8_t)packet.param1);
-            return MAV_RESULT_ACCEPTED;
-        }
-        return MAV_RESULT_FAILED;
-#endif
-        
     default:
         return GCS_MAVLINK::handle_command_long_packet(packet);
     }