drm/mgag200: Store vidrst flag in device info

Set new vidrst flag in device info for models that synchronize with
external sources (i.e., BMCs). In modesetting, set the corresponding
bits from the device-info flag.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220601112522.5774-10-tzimmermann@suse.de