drm/tegra: Use tegra_commit_dc() in output drivers

All output drivers have open-coded variants of this function, so export
it to remove some code duplication.

Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 3a3b2e7..5a0e96d 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -177,6 +177,7 @@
 void tegra_dc_enable_vblank(struct tegra_dc *dc);
 void tegra_dc_disable_vblank(struct tegra_dc *dc);
 void tegra_dc_cancel_page_flip(struct drm_crtc *crtc, struct drm_file *file);
+void tegra_dc_commit(struct tegra_dc *dc);
 
 struct tegra_output_ops {
 	int (*enable)(struct tegra_output *output);