NFSv4.2: Clean up: Move the encode_copy_commit() function

Move the function to be with the other encode_*() functions, instead of
in the middle of the nfs4_xdr_enc_*() section.

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