drm/nouveau/nouveau: fix memory leak in nouveau_crtc_page_flip()

Fix a memory leak in the nouveau_crtc_page_flip() error handling path.

Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --cc drivers/gpu/drm/nouveau/nouveau_display.c
Simple merge