OvmfPkg/QemuVideoDxe: VMWare SVGA device support

OvmfPkg/QemuVideoDxe: VMWare SVGA device support

In addition to the QXL, Cirrus, etc. VGA adapters, Qemu also implements
a basic version of VMWare's SVGA display device. Drivers for this
device exist for some guest OSes which do not support Qemu's other
display adapters, so supporting it in OVMF is useful in conjunction
with those OSes.

This change adds support for the SVGA device's framebuffer to
QemuVideoDxe's graphics output protocol implementation, based on
VMWare's documentation. The most basic initialisation, framebuffer
layout query, and mode setting operations are implemented.

The device relies on port-based 32-bit I/O, unfortunately on misaligned
addresses. This limits the driver's support to the x86 family of
platforms.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>