[serialization_lib] Remove unused type field from Pad and Clamp

This patch removes the "type" field from PadAttribute and ClampAttribute
because they are unused and unneeded.

Signed-off-by: Tai Ly <tai.ly@arm.com>
Change-Id: I378291b340ecee86824f25b3887aa4511207db23
diff --git a/python/tosa/PadAttribute.py b/python/tosa/PadAttribute.py
index c4084dc..301bf17 100644
--- a/python/tosa/PadAttribute.py
+++ b/python/tosa/PadAttribute.py
@@ -55,15 +55,8 @@
         o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
         return o == 0
 
-    # PadAttribute
-    def Type(self):
-        o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(6))
-        if o != 0:
-            return self._tab.Get(flatbuffers.number_types.Uint32Flags, o + self._tab.Pos)
-        return 0
-
 def PadAttributeStart(builder):
-    builder.StartObject(2)
+    builder.StartObject(1)
 
 def Start(builder):
     PadAttributeStart(builder)
@@ -80,12 +73,6 @@
 def StartPadConstVector(builder, numElems: int) -> int:
     return PadAttributeStartPadConstVector(builder, numElems)
 
-def PadAttributeAddType(builder, type):
-    builder.PrependUint32Slot(1, type, 0)
-
-def AddType(builder, type):
-    PadAttributeAddType(builder, type)
-
 def PadAttributeEnd(builder):
     return builder.EndObject()