gpio: nuvoton: Add Nuvoton NPCM sgpio driver

Add Nuvoton BMC NPCM7xx/NPCM8xx sgpio driver support.
Nuvoton NPCM SGPIO module is combine serial to parallel IC (HC595)
and parallel to serial IC (HC165), and use APB3 clock to control it.
This interface has 4 pins  (D_out , D_in, S_CLK, LDSH).
BMC can use this driver to increase 64 GPI pins and 64 GPO pins to use.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>