gpio: brcmstb: correct hwirq to bank map

gpio: brcmstb: correct hwirq to bank map

The brcmstb_gpio_hwirq_to_bank() function was designed to
accommodate the downward numbering of dynamic GPIOs by
traversing the bank list in the reverse order. However, the
dynamic numbering has changed to increment upward which can
produce an incorrect mapping.

The function is modified to no longer assume an ordering of
the list to accommodate either option.

Fixes: 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260127214656.447333-2-florian.fainelli@broadcom.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>