staging: lustre: ptlrpc: fix magic return value of ptlrpc_init_portals

Previously, when running 'modprobe lustre', it hit the following
error message which is becaue of network initialisation failure:
modprobe: ERROR: could not insert 'lustre': Input/output error

However, error code is there, just let it return to caller,
after this patch, error message will be something like:
modprobe: ERROR: could not insert 'lustre': Network is down

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5455
Reviewed-on: http://review.whamcloud.com/11337


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>