libceph: move schedule_delayed_work() in ceph_osdc_init()

ceph_osdc_stop() isn't called if ceph_osdc_init() fails, so we end up
with handle_osds_timeout() running on invalid memory if any one of the
allocations fails.  Call schedule_delayed_work() after everything is
setup, just before returning.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>