LU-14804 nodemap: do not return error for improper ACL

LU-14804 nodemap: do not return error for improper ACL

In nodemap_map_acl(), in case the ACL is incorrect, do nothing
and just return initial size to caller.

Lustre-change: https://review.whamcloud.com/44127
Lustre-commit: 601c48f3ecaefcb644f236344e139088f76a2a07

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I26aba9ce43e4a8878bfa47e145b1b44cfff89403
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44398
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>