hw/arm: Remove GPIO from unimplemented NPCM7XX

NPCM7XX GPIO devices have been implemented in hw/gpio/npcm7xx-gpio.c. So
we removed them from the unimplemented devices list.

Reviewed-by: Doug <Evans&lt;dje@google.com>
Reviewed-by: Tyrong <Ting&lt;kfting@nuvoton.com>
Signed-off-by: Hao <Wu&lt;wuhaotsh@google.com>
Message-id: 20210129005845.416272-2-wuhaotsh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>