NFS: fix the return value of nfs_file_fsync()

NFS: fix the return value of nfs_file_fsync()

commit 0702099bd86c33c2dcdbd3963433a61f3f503901 upstream.

By the commit af7fa16 2010-08-03 NFS: Fix up the fsync code
close(2) became returning the non-zero value even if it went well.
nfs_file_fsync() should return 0 when "status" is positive.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>