drm/bridge: tc358775: make standby GPIO optional

The stby pin is optional. It is only needed for power-up and down
sequencing. It is not needed, if the power rails cannot by dynamically
enabled.

Because the GPIO is now optional, remove the error message.

Signed-off-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240225062008.33191-6-tony@atomide.com

Author: mwalle

drivers/gpu/drm/bridge/tc358775.c

@@ -667,12 +667,9 @@ static int tc_probe(struct i2c_client *client)
 		return ret;
 	}
 
-	tc->stby_gpio = devm_gpiod_get(dev, "stby", GPIOD_OUT_HIGH);
-	if (IS_ERR(tc->stby_gpio)) {
-		ret = PTR_ERR(tc->stby_gpio);
-		dev_err(dev, "cannot get stby-gpio %d\n", ret);
-		return ret;
-	}
+	tc->stby_gpio = devm_gpiod_get_optional(dev, "stby", GPIOD_OUT_HIGH);
+	if (IS_ERR(tc->stby_gpio))
+		return PTR_ERR(tc->stby_gpio);
 
 	tc->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(tc->reset_gpio)) {