Empty val batch CUDA device fix (#7539)

Verified fix for https://github.com/ultralytics/yolov5/pull/7525#issuecomment-1106081123

Empty val batch CUDA device fix (#7539)
813eba85 · Glenn Jocher · GitHub · b804b36b · 813eba85
--- a/val.py
+++ b/val.py
@@ -227,7 +227,7 @@ def run(

            if npr == 0:
                if nl:
-                    stats.append((correct, *torch.zeros((3, 0))))
+                    stats.append((correct, *torch.zeros((3, 0), device=device)))
                continue

            # Predictions