LU-5455 ptlrpc: fix magic return value of ptlrpc_init_portals

LU-5455 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>
Change-Id: Ib0c893052b4cd4f2e9b427fb4ce91da356065351
Reviewed-on: http://review.whamcloud.com/11337
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
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>