fixed atan2f arguments

Change-Id: I0bb621e94d57594c3899e51d0c34ef43306cead0

src/math_functions.cpp

@@ -46,7 +46,7 @@ __device__ float asinhf(float x)
 }
 __device__ float atan2f(float y, float x)
 {
-    return hc::precise_math::atan2f(x, y);
+    return hc::precise_math::atan2f(y, x);
 }
 __device__ float atanf(float x)
 {