NFSD: Finish converting the NFSv2 GETACL result encoder

In the Linux kernel, the following vulnerability has been resolved: NFSD: Finish converting the NFSv2 GETACL result encoder The xdr_stream conversion inadvertently left some code that set the page_len of the send buffer. The XDR stream encoders should handle this automatically now. This oversight adds garbage past the end of the Reply message. Clients typically ignore the garbage, but NFSD does not need to send it, as it leaks stale memory contents onto the wire.