pinctrl: sh-pfc: Propagate errors on group config

On group configuration, bail out if setting one of the individual pins
fails. We don't need to roll-back, the pinctrl core will do this for us.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>