NFSD: Remove NFSD_PROC_ARGS_* macros

Clean up.

The PROC_ARGS macros were added when I thought that NFSD tracepoints
would be reporting endpoint information. However, tracepoints in the
RPC server now report transport endpoint information, so in general
there's no need for the upper layers to do that any more, and these
macros can be retired.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>