drm/nouveau/fbcon: zero-initialise the mode_cmd2 structure

This is tripping up the format modifier patches.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -315,7 +315,7 @@ nouveau_fbcon_create(struct drm_fb_helper *helper,
 	struct drm_framebuffer *fb;
 	struct nouveau_channel *chan;
 	struct nouveau_bo *nvbo;
-	struct drm_mode_fb_cmd2 mode_cmd;
+	struct drm_mode_fb_cmd2 mode_cmd = {};
 	int ret;
 
 	mode_cmd.width = sizes->surface_width;