Lint fix

The `span` field was only ever used to construct a TIR constant with a
known span, wasn't used at any of its callsites.

python/tvm/runtime/object_generic.py

@@ -38,7 +38,7 @@ def asobject(self):
 ObjectTypes = (ObjectBase, NDArrayBase, Module, ObjectRValueRef, PackedFuncBase, PyNativeObject)
 
 
-def convert_to_object(value, span=None):
+def convert_to_object(value):
     """Convert a Python value to corresponding object type.
 
     Type conversions performed by this function must *only* produce
@@ -54,9 +54,6 @@ def convert_to_object(value, span=None):
     value : str
         The value to be inspected.
 
-    span : Optional[Span]
-        The location of this itervar in the source code.
-
     Returns
     -------
     obj : Object