Fixed unused variables in ops (#4666)

* Fixed unused variables in ops

* Fixed test failure

torchvision/ops/boxes.py

@@ -323,7 +323,7 @@ def masks_to_boxes(masks: torch.Tensor) -> torch.Tensor:
     bounding_boxes = torch.zeros((n, 4), device=masks.device, dtype=torch.float)
 
     for index, mask in enumerate(masks):
-        y, x = torch.where(masks[index] != 0)
+        y, x = torch.where(mask != 0)
 
         bounding_boxes[index, 0] = torch.min(x)
         bounding_boxes[index, 1] = torch.min(y)

torchvision/ops/deform_conv.py

@@ -74,7 +74,7 @@ def deform_conv2d(
     pad_h, pad_w = _pair(padding)
     dil_h, dil_w = _pair(dilation)
     weights_h, weights_w = weight.shape[-2:]
-    _, n_in_channels, in_h, in_w = input.shape
+    _, n_in_channels, _, _ = input.shape
 
     n_offset_grps = offset.shape[1] // (2 * weights_h * weights_w)
     n_weight_grps = n_in_channels // weight.shape[1]