NFS: statfs error-handling fix

The nfs statfs function returns a success code on error, and fills the
output buffer with invalid values.  The attached patch makes it return a
correct error code instead.

Signed-off-by: Amnon Aaronsohn <amnonaar@gmail.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
 (Modified patch to reinstate the dprintk())