drm/bridge: ti-sn65dsi86: Make enable GPIO optional

The enable signal may not be controllable by the kernel. Make it
optional.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210624000304.16281-3-laurent.pinchart+renesas@ideasonboard.com

drivers/gpu/drm/bridge/ti-sn65dsi86.c

@@ -1459,7 +1459,8 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,
 		return dev_err_probe(dev, PTR_ERR(pdata->regmap),
 				     "regmap i2c init failed\n");
 
-	pdata->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+	pdata->enable_gpio = devm_gpiod_get_optional(dev, "enable",
+						     GPIOD_OUT_LOW);
 	if (IS_ERR(pdata->enable_gpio))
 		return dev_err_probe(dev, PTR_ERR(pdata->enable_gpio),
 				     "failed to get enable gpio from DT\n");