Merge remote-tracking branch...

Merge remote-tracking branch 'remotes/kraxel/tags/seabios-1.12.1-20190318-pull-request' into staging

seabios update for 4.0

# gpg: Signature made Mon 18 Mar 2019 13:07:53 GMT
# gpg:                using RSA key 4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>" [full]
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>" [full]
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>" [full]
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/seabios-1.12.1-20190318-pull-request:
  seabios: update binaries to 1.12.1
  seabios: turn off CONFIG_ATA_DMA
  seabios: update submodule to 1.12.1

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