drivers: gpio_pca95xx: add missing gpio_utils.h include

Include gpio_utils.h to fix a build failure:

gpio_pca95xx.c:490:20: warning: implicit declaration of
 function 'GPIO_PORT_PIN_MASK_FROM_NGPIOS'
 [-Wimplicit-function-declaration]
gpio_pca95xx.c:490:20: error: initializer element is not constant
   .port_pin_mask = GPIO_PORT_PIN_MASK_FROM_NGPIOS(
    DT_INST_##inst##_NXP_PCA95XX_NGPIOS), \

Signed-off-by: Göran Weinholt <goran.weinholt@endian.se>