Revert reversion of TensorFlow 2.9 update

With the errors caused by the previous TensorFlow 2.9 update
being fixed, we can proceed with the upgrade.

Signed-off-by: erik.andersson@arm.com <erik.andersson@arm.com>
Change-Id: Ie1f025e8d984efaebc68b8d051126d49bee6b2b8
diff --git a/ethosu/vela/tflite/CastOptions.py b/ethosu/vela/tflite/CastOptions.py
index 9060b51..70ae2e3 100644
--- a/ethosu/vela/tflite/CastOptions.py
+++ b/ethosu/vela/tflite/CastOptions.py
@@ -3,27 +3,17 @@
 # namespace: tflite
 
 import flatbuffers
-from flatbuffers.compat import import_numpy
-np = import_numpy()
 
 class CastOptions(object):
     __slots__ = ['_tab']
 
     @classmethod
-    def GetRootAs(cls, buf, offset=0):
+    def GetRootAsCastOptions(cls, buf, offset):
         n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
         x = CastOptions()
         x.Init(buf, n + offset)
         return x
 
-    @classmethod
-    def GetRootAsCastOptions(cls, buf, offset=0):
-        """This method is deprecated. Please switch to GetRootAs."""
-        return cls.GetRootAs(buf, offset)
-    @classmethod
-    def CastOptionsBufferHasIdentifier(cls, buf, offset, size_prefixed=False):
-        return flatbuffers.util.BufferHasIdentifier(buf, offset, b"\x54\x46\x4C\x33", size_prefixed=size_prefixed)
-
     # CastOptions
     def Init(self, buf, pos):
         self._tab = flatbuffers.table.Table(buf, pos)
@@ -42,19 +32,7 @@
             return self._tab.Get(flatbuffers.number_types.Int8Flags, o + self._tab.Pos)
         return 0
 
-def Start(builder): builder.StartObject(2)
-def CastOptionsStart(builder):
-    """This method is deprecated. Please switch to Start."""
-    return Start(builder)
-def AddInDataType(builder, inDataType): builder.PrependInt8Slot(0, inDataType, 0)
-def CastOptionsAddInDataType(builder, inDataType):
-    """This method is deprecated. Please switch to AddInDataType."""
-    return AddInDataType(builder, inDataType)
-def AddOutDataType(builder, outDataType): builder.PrependInt8Slot(1, outDataType, 0)
-def CastOptionsAddOutDataType(builder, outDataType):
-    """This method is deprecated. Please switch to AddOutDataType."""
-    return AddOutDataType(builder, outDataType)
-def End(builder): return builder.EndObject()
-def CastOptionsEnd(builder):
-    """This method is deprecated. Please switch to End."""
-    return End(builder)
\ No newline at end of file
+def CastOptionsStart(builder): builder.StartObject(2)
+def CastOptionsAddInDataType(builder, inDataType): builder.PrependInt8Slot(0, inDataType, 0)
+def CastOptionsAddOutDataType(builder, outDataType): builder.PrependInt8Slot(1, outDataType, 0)
+def CastOptionsEnd(builder): return builder.EndObject()