Merge remote-tracking branch 'kraxel/tags/pull-vga-20170511-1' into staging

make display updates thread safe, batch #2

# gpg: Signature made Thu 11 May 2017 03:41:51 PM BST
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* kraxel/tags/pull-vga-20170511-1:
  vga: fix display update region calculation
  sm501: make display updates thread safe
  tcx: make display updates thread safe
  cg3: make display updates thread safe

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>