drm/vmwgfx: Return true in function vmw_fence_obj_signaled()

Fix the following coccicheck warning:

drivers/gpu/drm/vmwgfx/vmwgfx_fence.c:518:9-10: WARNING: return of 0/1
in function 'vmw_fence_obj_signaled' with return type bool
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Roland Scheidegger <sroland@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_fence.c

@@ -515,7 +515,7 @@ bool vmw_fence_obj_signaled(struct vmw_fence_obj *fence)
 	struct vmw_fence_manager *fman = fman_from_fence(fence);
 
 	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
-		return 1;
+		return true;
 
 	vmw_fences_update(fman);