Motor didn't stop at target in rare cases -> fixed

Author: luni64

src/accelerators/LinStepAccelerator.h

@@ -55,7 +55,11 @@ int32_t LinStepAccelerator::updateSpeed(int32_t curPos)
         return v_tgt;
 
     //deceleration phase --------------------------------------
-    return sqrtf(two_a * ((stepsDone < delta_tgt - 1) ? delta_tgt - stepsDone - 2 : 0) + v_min2);
+    if(stepsDone < delta_tgt)
+        return sqrtf(two_a * ((stepsDone < delta_tgt - 1) ? delta_tgt - stepsDone - 2 : 0) + v_min2);
+
+    //we are done, make sure to return 0 to stop the step timer
+    return 0; 
 }
 
 uint32_t LinStepAccelerator::initiateStopping(int32_t curPos)