init/Kconfig: fix unmet direct dependencies

Commit 3c07bfce92a5 ("proc: make config PROC_CHILDREN depend on PROC_FS")
make config PROC_CHILDREN depend on PROC_FS.

When CONFIG_PROC_FS is not set and CONFIG_CHECKPOINT_RESTORE=y,
make menuconfig screams like this:

WARNING: unmet direct dependencies detected for PROC_CHILDREN
  Depends on [n]: PROC_FS [=n]
  Selected by [y]:
  - CHECKPOINT_RESTORE [=y]

CHECKPOINT_RESTORE would select PROC_CHILDREN which depends on PROC_FS,
so add depends on PROC_FS to CHECKPOINT_RESTORE to fix this.

Link: https://lkml.kernel.org/r/20220929070057.59044-1-renzhijie2@huawei.com
Fixes: 3c07bfce92a5 ("proc: make config PROC_CHILDREN depend on PROC_FS")
Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>