Merge remote-tracking branch 'remotes/kraxel/tags/fixes-20201104-pull-request' into staging

misc bugfixes for 5.2

# gpg: Signature made Wed 04 Nov 2020 15:46:33 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/fixes-20201104-pull-request:
  roms/Makefile: Add qboot to .PHONY list
  ati: check x y display parameter values
  vnc: fix resource leak when websocket channel error

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