Merge remote-tracking branch 'remotes/alistair/tags/pull-register-api-20200527' into...

A single patch to avoid clashes with the regiser field macros.

# gpg: Signature made Wed 27 May 2020 19:24:07 BST
# gpg:                using RSA key F6C4AC46D4934868D3B8CE8F21E10D29DF977054
# gpg: Good signature from "Alistair Francis <alistair@alistair23.me>" [full]
# Primary key fingerprint: F6C4 AC46 D493 4868 D3B8  CE8F 21E1 0D29 DF97 7054

* remotes/alistair/tags/pull-register-api-20200527:
  hw/registerfields: Prefix local variables with underscore in macros

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