SUNRPC: Determine value of "nrprocs" automatically

Clean up.

Just fixed a panic where the nrprocs field in a different upper layer
client was set by hand incorrectly.  Use the compiler-generated method
used by the other upper layer protocols.

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