drm/tegra: dsi: Don't disable regulator on ->exit()

The regulator is controlled as part of runtime PM, so it should not be
additionally disabled from the ->exit() callback.

Signed-off-by: Thierry Reding <[e-mail]>

drivers/gpu/drm/tegra/dsi.c

···
 	struct tegra_dsi *dsi = host1x_client_to_dsi(client);
 
 	tegra_output_exit(&dsi->output);
-	regulator_disable(dsi->vdd);
 
 	return 0;
 }