[CIFS] Fix mtime on cp -p when file data cached but written out too late

Kukks noticed that cp -p can write out file data too late, after the timestamp
is already set.  This was introduced as an unintentional sideeffect of the change
in an earlier patch (see below) which fixed some delayed return code propagation.

cea21805


Author: Jeff Layton <jlayton@redhat.com>
Date:   Tue Nov 20 23:19:03 2007 +0000

Acked-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>