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

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: d0593c363f04ccc4 ("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>