hw/misc: Add GPIOs for duty in NPCM7xx PWM

hw/misc: Add GPIOs for duty in NPCM7xx PWM

This patch adds GPIOs in NPCM7xx PWM module for its duty values.
The purpose of this is to connect it to the MFT module to provide
an input for measuring a PWM fan's RPM. Each PWM module has
NPCM7XX_PWM_PER_MODULE of GPIOs, each one corresponds to
one PWM instance and can connect to multiple fan instances in MFT.

Reviewed-by: Doug Evans <dje@google.com>
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20210311180855.149764-2-wuhaotsh@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>