drm/edid: Drop revision argument for drm_mode_std()

This argument is used to pass in the revision of the EDID, but since the
EDID is passed in as well, we can just as well get the revision from the
EDID structure directly.

While at it, update the kerneldoc comment.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>