sunrpc: Fix connect metrics

For TCP, the logic in xprt_connect_status is currently never invoked
to record a successful connection. Commit 2a491991 ("SUNRPC:
Return EAGAIN instead of ENOTCONN when waking up xprt->pending")
changed the way TCP xprt's are awoken after a connect succeeds.

Instead, change connection-oriented transports to bump connect_count
and compute connect_time the moment that XPRT_CONNECTED is set.

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