[MLBEDSW-2335] SoftMax int16

Added graph rewrite of Softmax for int16.

Change-Id: Id7885af6056a23e8b8362fb61ae94283251eb398
Signed-off-by: Fredrik Svedberg <fredrik.svedberg@arm.com>
diff --git a/ethosu/vela/tensor.py b/ethosu/vela/tensor.py
index 1a071e6..c2d6b6e 100644
--- a/ethosu/vela/tensor.py
+++ b/ethosu/vela/tensor.py
@@ -73,13 +73,14 @@
     Weights = 1
     FeatureMap = 2
     Scratch = 3
-    Size = 4
+    LUT = 4
+    Size = 5
 
     def display_name(self):
-        return ("Unknown", "Weights", "FeatureMap", "Scratch", "Size")[self.value]
+        return ("Unknown", "Weights", "FeatureMap", "Scratch", "LUT", "Size")[self.value]
 
     def identifier_name(self):
-        return ("unknown", "weights", "feature_map", "scratch", "size")[self.value]
+        return ("unknown", "weights", "feature_map", "scratch", "lut", "size")[self.value]
 
     def all():
         return (TensorPurpose.Weights, TensorPurpose.FeatureMap)