drm: use drm_file to tag vm-bos

Rather than using "struct file*", use "struct drm_file*" as tag VM tag for
BOs. This will pave the way for "struct drm_file*" without any "struct
file*" back-pointer.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20160901124837.680-3-dh.herrmann@gmail.com

drivers/gpu/drm/qxl/qxl_ttm.c

@@ -210,7 +210,8 @@ static int qxl_verify_access(struct ttm_buffer_object *bo, struct file *filp)
 {
 	struct qxl_bo *qbo = to_qxl_bo(bo);
 
-	return drm_vma_node_verify_access(&qbo->gem_base.vma_node, filp);
+	return drm_vma_node_verify_access(&qbo->gem_base.vma_node,
+					  filp->private_data);
 }
 
 static int qxl_ttm_io_mem_reserve(struct ttm_bo_device *bdev,