sunrpc: set cl_max_connect when cloning an rpc_clnt

If the initial attempt at trunking detection using the krb5i auth flavor
fails with -EACCES, -NFS4ERR_CLID_INUSE, or -NFS4ERR_WRONGSEC, then the
NFS client tries again using auth_sys, cloning the rpc_clnt in the
process.  If this second attempt at trunking detection succeeds, then
the resulting nfs_client->cl_rpcclient winds up having cl_max_connect=0
and subsequent attempts to add additional transport connections to the
rpc_clnt will fail with a message similar to the following being logged:

[502044.312640] SUNRPC: reached max allowed number (0) did not add
transport to server: 192.168.122.3

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Fixes: dc48e0ab ("SUNRPC enforce creation of no more than max_connect xprts")
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>