serial: use container_of to resolve uart_ip22zilog_port from uart_port

Use container_of instead of casting first structure member.

Signed-off-by: Fabian Frederick <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/ip22zilog.c

···
 /* The port lock is held and interrupts are disabled.  */
 static void ip22zilog_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
 	unsigned char set_bits, clear_bits;
 
···
 /* The port lock is held and interrupts are disabled.  */
 static void ip22zilog_stop_tx(struct uart_port *port)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 
 	up->flags |= IP22ZILOG_FLAG_TX_STOPPED;
 }
···
 /* The port lock is held and interrupts are disabled.  */
 static void ip22zilog_start_tx(struct uart_port *port)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
 	unsigned char status;
 
···
 /* The port lock is held.  */
 static void ip22zilog_enable_ms(struct uart_port *port)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
 	unsigned char new_reg;
 
···
 /* The port lock is not held.  */
 static void ip22zilog_break_ctl(struct uart_port *port, int break_state)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
 	unsigned char set_bits, clear_bits, new_reg;
 	unsigned long flags;
···
 ip22zilog_set_termios(struct uart_port *port, struct ktermios *termios,
 		      struct ktermios *old)
 {
-	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
+	struct uart_ip22zilog_port *up =
+		container_of(port, struct uart_ip22zilog_port, port);
 	unsigned long flags;
 	int baud, brg;