[AMDGPU][NFC] Correct typo in DWARF Extensions For Heterogeneous Debugging

[RamNalamothu]

Summary

The DW_AT_LLVM_address_space attribute is mentioned as DW_AT_address_space in
one of the notes.

llvm/docs/AMDGPUDwarfExtensionsForHeterogeneousDebugging.rst

.. note::
   type or reference type using ``DW_TAG_LLVM_address_class_type`` with a
   ``DW_AT_address_class`` attribute of ``DW_ADDR_LLVM_generic`` to match the
   language semantics.
 
   A new ``DW_AT_LLVM_address_space`` attribute could be defined that can be
   applied to pointer type, reference type, subprogram, and subprogram type to
   describe how objects having the given type are dereferenced or called (the
   role that ``DW_AT_address_class`` currently provides). The values of
-  ``DW_AT_address_space`` would be target architecture specific and the same as
-  used in ``DW_OP_xderef*``.
+  ``DW_AT_LLVM_address_space`` would be target architecture specific and the
+  same as used in ``DW_OP_xderef*``.
 
 .. note::
 
   Some additional changes will be made to support languages such as OpenCL/SyCL
   that allow address class pointer casting and queries.
 
   This requires the compiler to provide the mapping from address space to
   address class which may be runtime and not target architecture dependent. Some