SUNRPC: Remove xdr_align_data() and xdr_expand_hole()

These functions are no longer needed now that the NFS client places data
and hole segments directly.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>