BACKPORT: gpio: of: support gpio-ranges for multiple gpiochip devices

Some drivers (e.g. gpio-mt7621 and gpio-brcmstb) have multiple
gpiochip banks within a single device. Unfortunately, the
gpio-ranges property of the device node was being applied to
every gpiochip of the device with device relative GPIO offset
values rather than gpiochip relative GPIO offset values.

This commit makes use of the gpio_chip offset value which can be
non-zero for such devices to split the device node gpio-ranges
property into GPIO offset ranges that can be applied to each
of the relevant gpiochips of the device.

Bug: 353554778
Change-Id: I868f0cd8e4dc8003547a34f3cfd57eece731622f
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20240424185039.1707812-3-opendmb@gmail.com


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
(cherry picked from commit e818cd3c)
[danesh: Resolved minor conflict in drivers/gpio/gpiolib-of.c]
Signed-off-by: Danesh Petigara <danesh.petigara@broadcom.com>
Signed-off-by: Pierre Couillaud <pierre@broadcom.com>