staging/lustre/lnet: constify name argument of lstcon_group_find/lstcon_batch_find

This is part of original Lustre commit in external tree.

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3093
Lustre-change: http://review.whamcloud.com/6092
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>