drm/leases: Drop object_id validation for negative ids

Not exactly sure what's the aim here, but the canonical nil object has
id == 0, we don't use negative object ids for anything. Plus all
object_id are valided by the object_idr, there's nothing we need to do
on top of that ENOENT check a bit further down.

Spotted while typing exhaustive igt coverage for all these
corner-cases.

Cc: Keith Packard <keithp@keithp.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190228144910.26488-2-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_lease.c

@@ -403,11 +403,6 @@ static int fill_object_idr(struct drm_device *dev,
 	/* step one - get references to all the mode objects
 	   and check for validity. */
 	for (o = 0; o < object_count; o++) {
-		if ((int) object_ids[o] < 0) {
-			ret = -EINVAL;
-			goto out_free_objects;
-		}
-
 		objects[o] = drm_mode_object_find(dev, lessor_priv,
 						  object_ids[o],
 						  DRM_MODE_OBJECT_ANY);