gpio: mb86s7x: remove some dead code in mb86s70_gpio_to_irq()

The platform_get_irq() function never returns zero so delete this check.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/b7f3a78b-7163-42a0-bd09-8b3184f29661@stanley.mountain


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>