docs/zh_CN: Update zh_CN/process/submit-checklist.rst to 6.0-rc2

* update to commit 163ba35f ("doc: use KCFLAGS instead of
  EXTRA_CFLAGS to pass flags from command line")

Signed-off-by: Wu XiangCheng <bobwxc@email.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/Ywli7VfhQVPHKiGw@bobwxc.mipc


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