drm/nouveau: Don't include drm_legacy.h

Nouveau does not use DRM legacy code. Remove the rsp. include
statement.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210516185937.5644-3-tzimmermann@suse.de

drivers/gpu/drm/nouveau/nouveau_ttm.c

@@ -31,8 +31,6 @@
 #include "nouveau_mem.h"
 #include "nouveau_ttm.h"
 
-#include <drm/drm_legacy.h>
-
 #include <core/tegra.h>
 
 static void