driver: PS/2: npcx: add driver support for Nuvoton npcx family

The PS/2 module in npcx provides a hardware accelerator mechanism
including an 8-bit shift register, a state machine, and control logic
that handle both the incoming and outgoing data. The hardware
accelerator mechanism is shared by 4 PS/2 channels. To support it,
this CL separates the PS/2 driver into channel and controller drivers.
The controller driver is in charge of the PS/2 transaction. The channel
driver is in charge of the connection between the Zehpyr PS/2 API
interface and controller driver.

Signed-off-by: Jun Lin <CHLin56@nuvoton.com>