gpio: brcmstb: Utilize irqd_to_hwirq(d) instead of d->hwirq

gpio: brcmstb: Utilize irqd_to_hwirq(d) instead of d->hwirq

Consistently use irqd_to_hwirq(d) which is the recommended helper to
fetch the hardware IRQ number from an irq_data structure. While at it,
update the brcmstb_gpio_set_imask() function signature to use the proper
type for the "hwirq" argument rather than "unsigned int".

Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20260204164333.1146039-2-florian.fainelli@broadcom.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>