drm/virtio: move drm_connector_update_edid_property() call

drm_connector_update_edid_property can sleep, we must not
call it while holding a spinlock.  Move the callsite.

Fixes: b4b01b49 ("drm/virtio: add edid support")
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190405044602.2334-1-kraxel@redhat.com