OvmfPkg: VMWare SVGA display device register definitions

OvmfPkg: VMWare SVGA display device register definitions

This adds a header file defining symbolic constants for the VMWare SVGA
virtual display device in preparation for supporting it in
QemuVideoDxe.

It is mostly an extract of the file lib/vmware/svga_reg.h from commit
329dd537456f93a806841ec8a8213aed11395def of VMWare's vmware-svga
repository at git://git.code.sf.net/p/vmware-svga/git (See also
http://vmware-svga.sourceforge.net/ )

Only the bare essentials necessary for initialisation, modesetting and
framebuffer access have been kept from the original file; macro names
have been prefixed with VMWARE_SVGA_ instead of SVGA2_, and the enum
definition has been adapted to comply with EDK2 naming conventions.

The original file was released by VMWare under the MIT license, this
has been retained.

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>