drm/qxl: use suggested x/y offset properties to pass guest prefs

This passes the guest preferences for a where to place the
outputs through to userspace. Userspace would need to be updated
to take note of this information, X server and GNOME.

Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --cc drivers/gpu/drm/qxl/qxl_display.c
Simple merge