gpio: tc35894: Disable Direct KBD interrupts to enable gpio irq

On tc35894, have to disable direct keypad interrupts to make
it as general purpose interrupts functionality work.
if not, after chip reset, IRQST(0x91) will always 0x20,
IRQN always low level, can't be clear.

Configure DIRECTx to enable general purpose gpio mode,
else read GPIOMISx register always zero in irq routine.

verified on tc35894, need more test on other tc3589x.

Signed-off-by: dillon min <dillon.minfei@gmail.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>