MIPS patches for 5.1

- A pair of fixes,
- Add Huacai Chen as MIPS KVM maintainer,
- Add Jiaxun Yang as designated MIPS TCG reviewer.

CI jobs results:
. https://travis-ci.org/github/philmd/qemu/builds/708079271
. https://gitlab.com/philmd/qemu/-/pipelines/166528104
. https://cirrus-ci.com/build/6483996878045184



# gpg: Signature made Tue 14 Jul 2020 20:59:58 BST
# gpg:                using RSA key FAABE75E12917221DCFD6BB2E3E32C2CDEADC0DE
# gpg: Good signature from "Philippe Mathieu-Daudé (F4BUG) <f4bug@amsat.org>" [full]
# Primary key fingerprint: FAAB E75E 1291 7221 DCFD  6BB2 E3E3 2C2C DEAD C0DE

* remotes/philmd-gitlab/tags/mips-next-20200714:
  MAINTAINERS: Adjust MIPS maintainership (add Huacai Chen & Jiaxun Yang)
  target/mips: Fix ADD.S FPU instruction
  target/mips: Remove identical if/else branches

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>