Revert "gpio: mlxbf3: only get IRQ for device instance 0"

This reverts commit 10af0273.

While this change was merged, it is not the preferred solution.
During review of a similar change to the gpio-mlxbf2 driver, the
use of "platform_get_irq_optional" was identified as the preferred
solution, so let's use it for gpio-mlxbf3 driver as well.

Cc: stable@vger.kernel.org
Fixes: 10af0273 ("gpio: mlxbf3: only get IRQ for device instance 0")
Signed-off-by: David Thompson <davthompson@nvidia.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/8d2b630c71b3742f2c74242cf7d602706a6108e6.1754928650.git.davthompson@nvidia.com


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