nfsd4: remove redundant encode buffer size checking

Now that all op encoders can handle running out of space, we no longer
need to check the remaining size for every operation; only nonidempotent
operations need that check, and that can be done by
nfsd4_check_resp_size.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --cc fs/nfsd/nfs4proc.c
Simple merge

diff --cc fs/nfsd/nfs4xdr.c
Simple merge