stdvga: factor out mmio subregion init
virtio-gpu: add virtio gpu core code, 2d mode

# gpg: Signature made Wed Jun 10 10:03:11 2015 BST using RSA key ID D3E87138
# 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>"

* remotes/kraxel/tags/pull-vga-20150610-1:
  virtio-gpu/2d: add virtio gpu core code
  virtio: update headers, add virtio-gpu (2d)
  stdvga: factor out mmio subregion init
  stdvga: pass VGACommonState instead of PCIVGAState
  stdvga: fix offset in pci_vga_ioport_read

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