staging: lustre: return proper error code for LNet core

It is consider bad style in the linux kernel to
return -1 or a positive number for an error.
Instead return the appropriate error codes.

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6142
Reviewed-on: http://review.whamcloud.com/17626


Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>