pwm: sifive: Simplify code to determine the pwmchip's parent device

There is already a pointer to the pwmchip, make use of it directly
instead of using the struct pwm_sifive_ddata *ddata just obtained from
it. This also has the advantage of not using struct
pwm_sifive_ddata::chip any more which will be dropped soon.

Link: https://lore.kernel.org/r/78da507[e-mail]
Signed-off-by: Uwe Kleine-König <[e-mail]>

drivers/pwm/pwm-sifive.c

···
 	if (!enabled) {
 		ret = clk_enable(ddata->clk);
 		if (ret) {
-			dev_err(ddata->chip.dev, "Enable clk failed\n");
+			dev_err(chip->dev, "Enable clk failed\n");
 			return ret;
 		}
 	}