pwm: mtk-disp: Propagate errors in .get_state() to the caller

.get_state() can return an error indication. Make use of it to propagate
failing hardware accesses.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221130152148.2769768-9-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-mtk-disp.c

@@ -184,14 +184,14 @@ static int mtk_disp_pwm_get_state(struct pwm_chip *chip,
 	err = clk_prepare_enable(mdp->clk_main);
 	if (err < 0) {
 		dev_err(chip->dev, "Can't enable mdp->clk_main: %pe\n", ERR_PTR(err));
-		return 0;
+		return err;
 	}
 
 	err = clk_prepare_enable(mdp->clk_mm);
 	if (err < 0) {
 		dev_err(chip->dev, "Can't enable mdp->clk_mm: %pe\n", ERR_PTR(err));
 		clk_disable_unprepare(mdp->clk_main);
-		return 0;
+		return err;
 	}
 
 	rate = clk_get_rate(mdp->clk_main);