MLBEDSW-2935: LUT fusing with preceding operator

Allows fusing of LUT with a preceding operator regardless of
input/output scale.

Change-Id: Ia378adbb3fe61d71299feb085f7313377e0efa39
Signed-off-by: Louis Verhaard <louis.verhaard@arm.com>
diff --git a/ethosu/vela/operation.py b/ethosu/vela/operation.py
index 4b83b39..e7fd97c 100644
--- a/ethosu/vela/operation.py
+++ b/ethosu/vela/operation.py
@@ -200,6 +200,10 @@
 
         return ifm_tensor, ifm2_tensor, weight_tensor, bias_tensor, ofm_tensor
 
+    def get_ofm(self):
+        _, _, _, ofm = self.get_ifm_ifm2_weights_ofm()
+        return ofm
+
     def is_concat_op(self):
         return self.type in ("Concat", "ConcatV2", "QuantizedConcat", "ConcatTFLite", "PackReshaped")
 
@@ -361,3 +365,6 @@
             "Conv2DBackpropInputSwitchedBias",
             "FullyConnectedAct",
         )
+
+    def get_output_quantization(self):
+        return self.attrs.get("forced_output_quantization", self.get_ofm().quantization)