Add tosa identification numbers

Signed-off-by: Frederick Liardet <frederick.liardet@arm.com>
Change-Id: Idc5668fb01dc8dd657beb911d2cb9295f9275ac6
diff --git a/python/tosa_serializer.py b/python/tosa_serializer.py
index 6915c83..b11f9cd 100644
--- a/python/tosa_serializer.py
+++ b/python/tosa_serializer.py
@@ -60,6 +60,9 @@
     "FLOAT",
 ]
 
+# File identifier needs to be kept in sync with schema/tosa.fbs
+TOSA_GRAPH_IDENTIFIER = b"\x54\x4F\x53\x41"
+
 ByteMask = np.uint64(0xFF)
 
 
@@ -713,7 +716,7 @@
         TosaGraph.TosaGraphAddBlocks(builder, fbv_bb)
         graph = TosaGraph.TosaGraphEnd(builder)
 
-        self.builder.Finish(graph)
+        self.builder.Finish(graph, TOSA_GRAPH_IDENTIFIER)
         return self.builder.Output()
 
     def writeJson(self, tosa_filename):