uhttpd: Reload config after uhttpd-mod-ubus was added

uhttpd: Reload config after uhttpd-mod-ubus was added

Without this change the config is only committed, but the uhttpd daemon
is not reloaded. This reload is needed to apply the config. Without the
reload of uhttpd, the ubus server is not available over http and returns
a Error 404.

This caused problems when installing luci on the snapshots and
accessing it without reloading uhttpd.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit d25d281fd6686bda67636f6c1df918145b6cb738)