jobs: Fix a lock of call sync

Sometime the function jobs_leave missed to
wake up the process that expected the result.
It happened when that waiting thread was locked
in the epoll. That commit unlock it.

Bug-AGL: SPEC-2089

Change-Id: I6ab6a60a8c9ea3639143f282f90c7b77ed16853a
Signed-off-by: Jose Bollo <jose.bollo@iot.bzh>
Signed-off-by: Clément Bénier <clement.benier@iot.bzh>