drm/i915: Return a drm_mode_status enum in the mode_valid vfuncs

We had some mode_valid() vfuncs returning an int, others the enum. Let's
use the latter everywhere.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
7 files changed