drm: Store vendor IDs directly in the EDID quirk structure

EDID vendor IDs are always 3 characters long (4 with the terminating
0).  It doesn't make any sense to have a (possibly 8-byte) pointer
to the ID string in the quirk structure.

Signed-off-by: Ian Pilcher <arequipeno@gmail.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>