QemuVideo: Add support for the bochs dispi interface

QemuVideo: Add support for the bochs dispi interface

Add code to handle qemu-emulated vga cards supporting the bochs dispi
interface (standard vga, qxl vga).  This requires qemu 1.3+ which
provides the bochs dispi interface data register on a aligned io
address.  See
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=df9ffb726ff13f850b8829be1bc85ed621b903ac

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13968 6f19259b-4bc3-4df7-8a09-765794883524