pinctrl: renesas: Use int type to store negative error codes

Change the 'ret' variable in sh_pfc_pinconf_group_set() from unsigned
int to int, as it needs to store either negative error codes or zero
returned by sh_pfc_pinconf_set().

No effect on runtime.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Fixes: d0593c3 ("pinctrl: sh-pfc: Propagate errors on group config")
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250831084958.431913-4-rongqianfeng@vivo.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Author: qianfengrong

drivers/pinctrl/renesas/pinctrl.c

@@ -726,7 +726,8 @@ static int sh_pfc_pinconf_group_set(struct pinctrl_dev *pctldev, unsigned group,
 	struct sh_pfc_pinctrl *pmx = pinctrl_dev_get_drvdata(pctldev);
 	const unsigned int *pins;
 	unsigned int num_pins;
-	unsigned int i, ret;
+	unsigned int i;
+	int ret;
 
 	pins = pmx->pfc->info->groups[group].pins;
 	num_pins = pmx->pfc->info->groups[group].nr_pins;