pinctrl: at91: make it work with current gpiolib

pinctrl-at91 currently does not support the gpio-groups devicetree
property and has no pin-range.
Because of this at91 gpios stopped working since patch
commit 2ab73c6d ("gpio: Support GPIO controllers without pin-ranges")
This was discussed in the patches
commit fc328a7d ("gpio: Revert regression in sysfs-gpio (gpiolib.c)")
commit 56e337f2 ("Revert "gpio: Revert regression in sysfs-gpio (gpiolib.c)"")

As a workaround manually set pin-range via gpiochip_add_pin_range() until
a) pinctrl-at91 is reworked to support devicetree gpio-groups
b) another solution as mentioned in
commit 56e337f2 ("Revert "gpio: Revert regression in sysfs-gpio (gpiolib.c)"")
is found

Signed-off-by: Thomas Blocher <thomas.blocher@ek-dev.de>
Link: https://lore.kernel.org/5b992862-355d-f0de-cd3d-ff99e67a4ff1@ek-dev.de


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>