[SCSI] libfc: correctly handle incoming PLOGI request.

libfc receives PLOGIs from switches which are trying to discover what
kind of devices are present, and from other initiators to find out
if we're a target.

As an initiator, some argue we don't need to handle incoming PLOGI
requests, and we currently reject them from unknown remote ports,
but accept them is we're in the middle of a PLOGI to the remote port.

For eventual target implementations, we want to handle them always.

For incoming PLOGI, don't fail if the rport_priv doesn't exist.
Just create it and go become READY without going through PRLI.  If
PRLI occurs, then our roles will be set and we'll become READY again.

Also, allow incoming PRLI in RTV state.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>