EX-5249 utils: don't complain for missing lustre.pin

EX-5249 utils: don't complain for missing lustre.pin

Don't print an error when running "lfs pcc status" against an older
server without the "lustre.pin" xattr returns EOPNOTSUPP.

Test-Parameters: trivial testlist=sanity-pcc serverversion=2.14.0-ddn23
Fixes: f9970c0a70 ("EX-5249 utils: show pin information in 'lfs pcc state' command")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Iab235b8be497386752915baeb31347cf8137eed0
Reviewed-on: https://review.whamcloud.com/47723
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Feng, Lei <flei@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>