qxl: split monitors_config object creation out.

This splits the creation of the monitors config object out so we can
re-use it across suspend/resume later.

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

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

diff --cc drivers/gpu/drm/qxl/qxl_drv.h
Simple merge