input: ps2-gpio: use ktime for IRQ timekeeping

[Danilo Krummrich]

This patch series implements the usage of ktime for IRQ timekeeping to
overcome:

(1) The resolution limitations of jiffies.
(2) Potential spurious IRQs generated by gpio controllers.

Besides that, based on the newly implemented timekeeping, it fixes a wrongly
suspected extra clock cycle for TX transfers and a race condition when
starting an immediate TX transfer based on data received from an RX transfer.