scsi: iscsi_tcp: Remove a set-but-not-used variable

This patch avoids that gcc reports the following warning when
building with W=1:

drivers/scsi/iscsi_tcp.c:166:24: warning: variable ?session? set but not used [-Wunused-but-set-variable]

Signed-off-by: Bart Van Assche <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Cc: Lee Duncan <[e-mail]>
Cc: Johannes Thumshirn <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/iscsi_tcp.c

···
 	struct iscsi_tcp_conn *tcp_conn;
 	struct iscsi_sw_tcp_conn *tcp_sw_conn;
 	struct iscsi_conn *conn;
-	struct iscsi_session *session;
 	void (*old_state_change)(struct sock *);
 
 	read_lock_bh(&sk->sk_callback_lock);
···
 		read_unlock_bh(&sk->sk_callback_lock);
 		return;
 	}
-	session = conn->session;
 
 	iscsi_sw_sk_state_check(sk);