Temporarily revert: r209129 - [mips][mips64r6] Sorted *_ENC, *_DESC classes and tests

After discussion with Zoran, we have decided to temporarily revert this commit.
It's causing some difficult to resolve conflicts and we are under time pressure
to deliver an initial MIPS64r6 compiler.

We will re-apply an equivalent patch once the time pressure has passed.

llvm-svn: 209211