d3d8/tests: Fix copy&paste issue in compare_mode (cppcheck).

dlls/d3d8/tests/device.c

@@ -1281,7 +1281,7 @@ static int compare_mode(const void *a, const void *b)
     const struct mode *mode_a = a;
     const struct mode *mode_b = b;
     unsigned int w = mode_a->w - mode_b->w;
-    unsigned int h = mode_b->h - mode_b->h;
+    unsigned int h = mode_a->h - mode_b->h;
     return abs(w) >= abs(h) ? -w : -h;
 }