s3: smbd: Unix extensions attempts to change wrong field in fchown call.

s3: smbd: Unix extensions attempts to change wrong field in fchown call.

Cut and paste error.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13375

Reported-by: Rungta, Vandana <vrungta@amazon.com>
Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: David Disseldorp <ddiss@samba.org>
Autobuild-User(master): David Disseldorp <ddiss@samba.org>
Autobuild-Date(master): Tue Apr 10 00:45:56 CEST 2018 on sn-devel-144

(cherry picked from commit 3227b110d065500ed84fc70063da70ab35823a2e)

Autobuild-User(v4-6-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-6-test): Wed Apr 11 16:55:21 CEST 2018 on sn-devel-144