docs/zh_CN: Update the translation of gpio to 6.0-rc1

Update to commit 5513b411 ("Documentation: rename pinctl to
pin-control")
Move .../zh_CN/gpio.txt to .../zh_CN/driver-api/gpio/legacy.rst
Translate .../driver-api/index.rst into Chinese.
Translate .../driver-api/gpio/index.rst into Chinese.

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Reviewed-by: Wu XiangCheng <bobwxc@email.cn>
Link: https://lore.kernel.org/r/20220817020830.799468-1-siyanteng@loongson.cn


Signed-off-by: Jonathan Corbet <corbet@lwn.net>