drm: Forbid legacy MAP functions for DRIVER_MODESET

Like in

commit 0e97598
Author: Peter Antoine <peter.antoine@intel.com>
Date:   Tue Jun 23 08:18:49 2015 +0100

    drm: Turn off Legacy Context Functions

we need to again make an exception for nouveau, but everyone else
really doesn't need this.

Dave Airlie dug out again why we need this: The problem is the legacy
dri1 open function the nouveau ddx called, and the problematic code is
actually in the X server itself. It was only fixed in

commit b1a630b48210d6a3c44994fce1b73273000ace5c
Author: Dave Airlie <airlied@redhat.com>
Date:   Wed Nov 7 14:45:14 2012 +1000

    nouveau: drop DRI1 device open interface.

Cc: Peter Antoine <peter.antoine@intel.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461691808-12414-5-git-send-email-daniel.vetter@ffwll.ch
Link: http://patchwork.freedesktop.org/patch/msgid/1461691808-12414-6-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_bufs.c

@@ -396,6 +396,10 @@ int drm_legacy_addmap_ioctl(struct drm_device *dev, void *data,
 	if (!(capable(CAP_SYS_ADMIN) || map->type == _DRM_AGP || map->type == _DRM_SHM))
 		return -EPERM;
 
+	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
+	    drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
 	err = drm_addmap_core(dev, map->offset, map->size, map->type,
 			      map->flags, &maplist);
 
@@ -438,6 +442,10 @@ int drm_legacy_getmap_ioctl(struct drm_device *dev, void *data,
 	int idx;
 	int i;
 
+	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
+	    drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
 	idx = map->offset;
 	if (idx < 0)
 		return -EINVAL;
@@ -569,6 +577,10 @@ int drm_legacy_rmmap_ioctl(struct drm_device *dev, void *data,
 	struct drm_map_list *r_list;
 	int ret;
 
+	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
+	    drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
 	mutex_lock(&dev->struct_mutex);
 	list_for_each_entry(r_list, &dev->maplist, head) {
 		if (r_list->map &&