Add support for MIPS Release 6 ISA (From OE-Core rev: fcb67508be00cdd22181d6c9e4c3d29dfa578b45) Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>