drm/i915/gvt: Enable vfio edid for all GVT supported platform

All GVT supported platform has virtual display which should be
able to handle VFIO edid region. Enable this for all supported platform.

Cc: Hang Yuan <hang.yuan@linux.intel.com>
Cc: Fred Gao <fred.gao@intel.com>
Reviewed-by: Hang Yuan <hang.yuan@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20191202070109.73924-3-zhenyuw@linux.intel.com