NFSD: pass null terminated buf to kstrtouint()

commit 9959ba0c241a71c7ed8133401cfbbee2720da0b5 upstream.

The 'buf' is prepared with null termination with intention of using it for
this purpose, but 'name' is passed instead!

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>