nfs: fix sunrpc/clnt.c kernel-doc warnings

Fix new kernel-doc warnings in clnt.c:

  Warning(net/sunrpc/clnt.c:561): No description found for parameter 'flavor'
  Warning(net/sunrpc/clnt.c:561): Excess function parameter 'auth' description in 'rpc_clone_client_set_auth'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: linux-nfs@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>