Copter: remove redundant check; we will never failsafe_ekf_event if disarmed

See line 37

ArduCopter/ekf_check.cpp

@@ -129,11 +129,6 @@ void Copter::failsafe_ekf_event()
         return;
     }
 
-    // do nothing if motors disarmed
-    if (!motors->armed()) {
-        return;
-    }
-
     // do nothing if not in GPS flight mode and ekf-action is not land-even-stabilize
     if ((control_mode != LAND) && !mode_requires_GPS(control_mode) && (g.fs_ekf_action != FS_EKF_ACTION_LAND_EVEN_STABILIZE)) {
         return;