pinctrl: stmfx: Do not check for 0 return after calling platform_get_irq()

Since commit ce753ad1 ("platform: finally disallow IRQ0 in
platform_get_irq() and its ilk"), there is no possible for
platform_get_irq() to return 0. Use the return value
from platform_get_irq().

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20230803094304.733371-1-ruanjinjie@huawei.com


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