After fixing (r306173) a failing test in the lld test suite (r306173),
reland r306095.
Original commit message:
[mips] Fix register positions in the aui/daui instructions
Swapped the position of the rt and rs register in the aui/daui
instructions for mips32r6 and mips64r6. With this change, the format of
the generated instructions complies with specifications and GCC.
Patch by Milos Stojanovic.
llvm-svn: 306174