drm/vboxvideo: Use drm_fb_helper_fill_info

drm/vboxvideo: Use drm_fb_helper_fill_info

This should not result in any changes.

v2: Rebase over vbox changes - vbox gained it's own line to fill
fix.id.

v3: Rebase

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (v2)
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190326132008.11781-20-daniel.vetter@ffwll.ch