iscsi-target: Initial traditional TCP conversion to iscsit_transport

This patch performs the initial conversion of existing traditional iscsi
to use iscsit_transport API callers.  This includes:

- iscsi-np cleanups for iscsit_transport_type
- Add iscsi-np transport calls w/ ->iscsit_setup_up() and ->iscsit_free_np()
- Convert login thread process context to use ->iscsit_accept_np() for
  connections with pre-allocated struct iscsi_conn
- Convert existing socket accept code to iscsit_accept_np()
- Convert login RX/TX callers to use ->iscsit_get_login_rx() and
  ->iscsit_put_login_tx() to exchange request/response PDUs
- Convert existing socket login RX/TX calls into iscsit_get_login_rx()
  and iscsit_put_login_tx()
- Change iscsit_close_connection() to invoke ->iscsit_free_conn() +
  iscsit_put_transport() calls.
- Add iscsit_register_transport() + iscsit_unregister_transport() calls
  to module init/exit

v4 changes:

- Add missing iscsit_put_transport() call in iscsi_target_setup_login_socket()
  failure case

v2 changes:

- Update module init/exit to use register_transport() + unregister_transport()

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
index ee8f8c6..439260b 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.c
+++ b/drivers/target/iscsi/iscsi_target_tpg.c
@@ -31,6 +31,8 @@
 #include "iscsi_target.h"
 #include "iscsi_target_parameters.h"
 
+#include <target/iscsi/iscsi_transport.h>
+
 struct iscsi_portal_group *iscsit_alloc_portal_group(struct iscsi_tiqn *tiqn, u16 tpgt)
 {
 	struct iscsi_portal_group *tpg;
@@ -508,7 +510,7 @@
 
 	pr_debug("CORE[%s] - Added Network Portal: %s:%hu,%hu on %s\n",
 		tpg->tpg_tiqn->tiqn, np->np_ip, np->np_port, tpg->tpgt,
-		(np->np_network_transport == ISCSI_TCP) ? "TCP" : "SCTP");
+		np->np_transport->name);
 
 	return tpg_np;
 }
@@ -522,7 +524,7 @@
 
 	pr_debug("CORE[%s] - Removed Network Portal: %s:%hu,%hu on %s\n",
 		tpg->tpg_tiqn->tiqn, np->np_ip, np->np_port, tpg->tpgt,
-		(np->np_network_transport == ISCSI_TCP) ? "TCP" : "SCTP");
+		np->np_transport->name);
 
 	tpg_np->tpg_np = NULL;
 	tpg_np->tpg = NULL;