drm: Unify and fix idr error handling

The error handling code w.r.t. idr usage looks inconsistent.

In the case of drm_mode_object_get() and drm_ctxbitmap_next() the error
handling is also incomplete.

Unify the code to follow the same pattern always.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 4d4e8b0..a9ca1b8 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -227,7 +227,7 @@
 again:
 	if (idr_pre_get(&dev->mode_config.crtc_idr, GFP_KERNEL) == 0) {
 		DRM_ERROR("Ran out memory getting a mode number\n");
-		return -EINVAL;
+		return -ENOMEM;
 	}
 
 	mutex_lock(&dev->mode_config.idr_mutex);
@@ -235,6 +235,8 @@
 	mutex_unlock(&dev->mode_config.idr_mutex);
 	if (ret == -EAGAIN)
 		goto again;
+	else if (ret)
+		return ret;
 
 	obj->id = new_id;
 	obj->type = obj_type;