scsi: target: iscsi: Fix clang -Wformat warnings

When building with Clang we encounter these warnings:
| drivers/target/iscsi/iscsi_target_login.c:719:24: error: format
| specifies type 'unsigned short' but the argument has type 'int'
| [-Werror,-Wformat] " from node: %s\n", atomic_read(&sess->nconn),
-
| drivers/target/iscsi/iscsi_target_login.c:767:12: error: format
| specifies type 'unsigned short' but the argument has type 'int'
| [-Werror,-Wformat] " %s\n", atomic_read(&sess->nconn),
-
| drivers/target/iscsi/iscsi_target.c:4365:12: error: format specifies
| type 'unsigned short' but the argument has type 'int' [-Werror,-Wformat]
| " %s\n", atomic_read(&sess->nconn)

For all warnings, the format specifier is '%hu' which describes an unsigned
short. The resulting type of atomic_read is an int. The proposed fix is to
listen to Clang and swap the format specifier.

Link: ClangBuiltLinux#378
Link: https://lore.kernel.org/r/20220718180421.49697-1-justinstitt@google.com
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: JustinStitt

drivers/target/iscsi/iscsi_target.c

@@ -4361,7 +4361,7 @@ int iscsit_close_connection(
 
 	spin_lock_bh(&sess->conn_lock);
 	atomic_dec(&sess->nconn);
-	pr_debug("Decremented iSCSI connection count to %hu from node:"
+	pr_debug("Decremented iSCSI connection count to %d from node:"
 		" %s\n", atomic_read(&sess->nconn),
 		sess->sess_ops->InitiatorName);
 	/*

drivers/target/iscsi/iscsi_target_login.c

@@ -715,7 +715,7 @@ void iscsi_post_login_handler(
 
 		list_add_tail(&conn->conn_list, &sess->sess_conn_list);
 		atomic_inc(&sess->nconn);
-		pr_debug("Incremented iSCSI Connection count to %hu"
+		pr_debug("Incremented iSCSI Connection count to %d"
 			" from node: %s\n", atomic_read(&sess->nconn),
 			sess->sess_ops->InitiatorName);
 		spin_unlock_bh(&sess->conn_lock);
@@ -763,7 +763,7 @@ void iscsi_post_login_handler(
 	spin_lock_bh(&sess->conn_lock);
 	list_add_tail(&conn->conn_list, &sess->sess_conn_list);
 	atomic_inc(&sess->nconn);
-	pr_debug("Incremented iSCSI Connection count to %hu from node:"
+	pr_debug("Incremented iSCSI Connection count to %d from node:"
 		" %s\n", atomic_read(&sess->nconn),
 		sess->sess_ops->InitiatorName);
 	spin_unlock_bh(&sess->conn_lock);