iscsi: Simplify include relationships to avoid cyclic inclusion

Including tgt_node.h in iscsi.h will prevent us from including
iscsi.h in tgt_node.h. Subsequent patches will require tgt_node.h
to refer the macro constants in iscsi.h.

Hence
- remove inclusion of tgt_node.h from iscsi.h,
- add inclusion of spdk/scsi.h to iscsi.h, and
- remove inclusion of spdk/scsi.h from tgt_node.h

Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: I5ac808a83754c157e4140bcd2a83c4d210e30d91
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/459704
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>

lib/iscsi/iscsi.h

@@ -42,8 +42,8 @@
 #include "spdk/event.h"
 #include "spdk/thread.h"
 
+#include "spdk/scsi.h"
 #include "iscsi/param.h"
-#include "iscsi/tgt_node.h"
 
 #include "spdk/assert.h"
 #include "spdk/dif.h"

lib/iscsi/iscsi_subsystem.c

@@ -43,6 +43,7 @@
 #include "iscsi/portal_grp.h"
 #include "iscsi/conn.h"
 #include "iscsi/task.h"
+#include "iscsi/tgt_node.h"
 
 #include "spdk_internal/event.h"
 #include "spdk_internal/log.h"

lib/iscsi/tgt_node.h

@@ -37,8 +37,6 @@
 
 #include "spdk/stdinc.h"
 
-#include "spdk/scsi.h"
-
 struct spdk_iscsi_conn;
 struct spdk_iscsi_init_grp;
 struct spdk_iscsi_portal_grp;