drm/amdgpu: use crtc directly in drm_crtc_vblank_put()

We don't need to use &amdgpu_crtc->base there as crtc is available
in the function.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1465308482-15104-9-git-send-email-gustavo@padovan.org

drivers/gpu/drm/amd/amdgpu/amdgpu_display.c

@@ -268,7 +268,7 @@ int amdgpu_crtc_page_flip(struct drm_crtc *crtc,
 	return 0;
 
 vblank_cleanup:
-	drm_crtc_vblank_put(&amdgpu_crtc->base);
+	drm_crtc_vblank_put(crtc);
 
 pflip_cleanup:
 	if (unlikely(amdgpu_bo_reserve(new_rbo, false) != 0)) {