vga: catch depth 0
hw/display: add new bochs-display device
some cleanups.

# gpg: Signature made Thu 24 May 2018 16:45:46 BST
# gpg:                using RSA key 4CB6D8EED3E87138
# 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

* remotes/kraxel/tags/vga-20180524-pull-request:
  MAINTAINERS: add vga entries
  bochs-display: add pcie support
  bochs-display: add dirty tracking support
  hw/display: add new bochs-display device
  vga-pci: use PCI_VGA_MMIO_SIZE
  vga: move bochs vbe defines to header file
  vga: catch depth 0

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