Clean up: have the set up routines explicitly pass the strings to be used
for the transport name and NETID.  This removes a number of conditionals
and dependencies on rpc_xprt.prot, which is overloaded.

Tighten up type checking on the address_strings array while we're at it.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>