gpio: pca953x: Switch to bitops in IRQ callbacks

Since we have driver converted to use bitmap API we must use
traditional bit operations (set_bit(), clear_bit(), etc.)
against it.

Currently IRQ callbacks are missed in the conversion and
thus broken.

Let's fix it right here right now.

Fixes: 35d13d94

 ("gpio: pca953x: convert to use bitmap API")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>