Add Nuvoton BMC NPCM750/730/715/705 Pulse Width Modulation (PWM)
and Fan tacho driver.
The Nuvoton BMC NPCM750/730/715/705 supports 8 PWM controller outputs
and 16 Fan controller inputs.
The driver provides a sysfs entries through which the user can
configure the duty-cycle value from 0(off) and 255(full speed)
and read the fan tacho rpm value.