Update Detections() times=None (#2570)

Fix for results.tolist() method breaking after YOLOv5 Hub profiling PRshttps://github.com/ultralytics/yolov5/pull/2460 https://github.com/ultralytics/yolov5/pull/2459 and

models/common.py

@@ -235,7 +235,7 @@ class autoShape(nn.Module):
 
 class Detections:
     # detections class for YOLOv5 inference results
-    def __init__(self, imgs, pred, files, times, names=None, shape=None):
+    def __init__(self, imgs, pred, files, times=None, names=None, shape=None):
         super(Detections, self).__init__()
         d = pred[0].device  # device
         gn = [torch.tensor([*[im.shape[i] for i in [1, 0, 1, 0]], 1., 1.], device=d) for im in imgs]  # normalizations