MLBEDSW-2637 Utilise new tensor and operator funcs

add_input_tensor, set_output_tensor, create_const_tensor and
create_reshape_tensor have recently been added.
This replaces all found existing instances with these new helper
functions

Signed-off-by: Michael McGeagh <michael.mcgeagh@arm.com>
Change-Id: If33be8dbf237b2087b562b03cdeb51da1f99a786
diff --git a/ethosu/vela/pass_packing.py b/ethosu/vela/pass_packing.py
index fab00e0..8e108db 100644
--- a/ethosu/vela/pass_packing.py
+++ b/ethosu/vela/pass_packing.py
@@ -456,8 +456,7 @@
             avgpool_op.attrs["explicit_padding"] = [0, 0, 0, 0]
             avgpool_out = inp.clone("_avgpooled")
             avgpool_out.consumer_list.append(op)
-            avgpool_out.ops = [avgpool_op]
-            avgpool_op.outputs = [avgpool_out]
+            avgpool_op.set_output_tensor(avgpool_out)
 
             op.inputs[0] = avgpool_out
             ops_list.insert(0, avgpool_op)