media: cec-gpio: use disable/enable_irq

Due to limitations in gpiolib it was impossible to disable the interrupt of
an input gpio and then switch it to gpio output and drive it. The only way
to achieve that was to free the interrupt first, then switch the direction.

When going back to gpio input and using interrupts to read the gpio pin you
had to request the irq again.

This limitation was lifted in gpiolib in kernel 4.20, but the cec-gpio driver
was still using the old workaround implementation.

This patch updates the cec-gpio driver to just enable and disable the irq.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>