drm: qxl: Drop duplicated device pointer attribute

qxl_device duplicates a pointer to struct device, which is not needed
since we already have it in the drm_device structure.  Clean it up.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170127010548.27970-2-krisman@collabora.co.uk


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>