NFSD: Remove the cap on number of operations per NFSv4 COMPOUND

NFSD: Remove the cap on number of operations per NFSv4 COMPOUND

This limit has always been a sanity check; in nearly all cases a
large COMPOUND is a sign of a malfunctioning client. The only real
limit on COMPOUND size and complexity is the size of NFSD's send
and receive buffers.

However, there are a few cases where a large COMPOUND is sane. For
example, when a client implementation wants to walk down a long file
pathname in a single round trip.

A small risk is that now a client can construct a COMPOUND request
that can keep a single nfsd thread busy for quite some time.

Suggested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>