init: change return value when starting corosync

When corosync is started by systemd, it would be considered
as failed because it returns a non-zero value, even though it
starts sucessfully.

Signed-off-by: Lidong Zhong <lzhong@suse.com>
Signed-off-by: Xia Li<xli@suse.com>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>