[commit] ppc64: Fix stwux encoding

[Pedro Franco de Carvalho]

Thank you for this patch!

The mask was still too permissive (see PR gdb/18295), so I submitted
another patch fixing that. Sorry I didn't see this before!

Previously the stdux mask also allowed stwux (and more), and the if body
was the same, so it was accidentally working for stwux, despite the
tautological compare.

-- 
Pedro Franco de Carvalho