ksmbd-tools: Fix ksmbd service is semi-killed at system startup

ksmbd-tools: Fix ksmbd service is semi-killed at system startup

The configuration for the ksmbd service is auto-generated when
the OpenWRT configuration changes, and also during startup,
hence ksmbd.init has to reload the kernel module. It does that by
calling kill_server, which does not perform cleanup. This results
in ksmbd being killed but not restarted properly during boot.
This patch resolves the issue by using stop_service, which performs
proper cleanup.

https://forum.openwrt.org/t/ksmbd-samba3-4-alternative-ex-cifsd-smbd-package-support-thread/51695/68

Signed-off-by: Georgi Valkov <gvalkov@abv.bg>