staging: lustre: handle lnet_check_routes() errors

After adding a route, lnet_check_routes() is called to ensure that
the route added doesn't invalidate the routing configuration.  If
lnet_check_routes() fails then the route just added, which caused the
current configuration to be invalidated is deleted, and an error
is returned to the user.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6218
Reviewed-on: http://review.whamcloud.com/13445


Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>