pinctrl: fix example .get_group_pins implementation signature

commit 838d030bda9e2da5f9dcf7251f4e117c6258cb2f upstream.

The callback function signature has changed in commit a5818a8bd0 (pinctrl:
get_group_pins() const fixes)

Fixes: a5818a8bd0 ('pinctrl: get_group_pins() const fixes')
Cc: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --cc Documentation/pinctrl.txt
Simple merge