8250: use correct value for PORT_BRCM_TRUMANAGE

When backporting commit ebebd49a ('8250/16?50: Add support for
Broadcom TruManage redirected serial port') I took the next
available port type number for PORT_BRCM_TRUMANAGE (22).

However, the 8250 port type numbers are exposed to userland through
the TIOC{G,S}SERIAL ioctls and so must remain stable.  Redefine
PORT_BRCM_TRUMANAGE as 25, matching mainline as of commit
85f02440.

This leaves port types 22-24 within the valid range for 8250 but not
implemented there.  Change serial8250_verify_port() to specifically
reject these and change serial8250_type() to return "unknown" for them
(though I'm not sure why it would ever see them).
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/tty/serial/8250.c

@@ -2695,7 +2695,7 @@ serial8250_verify_port(struct uart_port *port, struct serial_struct *ser)
 	if (ser->irq >= nr_irqs || ser->irq < 0 ||
 	    ser->baud_base < 9600 || ser->type < PORT_UNKNOWN ||
 	    ser->type >= ARRAY_SIZE(uart_config) || ser->type == PORT_CIRRUS ||
-	    ser->type == PORT_STARTECH)
+	    ser->type == PORT_STARTECH || uart_config[ser->type].name == NULL)
 		return -EINVAL;
 	return 0;
 }
@@ -2705,7 +2705,7 @@ serial8250_type(struct uart_port *port)
 {
 	int type = port->type;
 
-	if (type >= ARRAY_SIZE(uart_config))
+	if (type >= ARRAY_SIZE(uart_config) || uart_config[type].name == NULL)
 		type = 0;
 	return uart_config[type].name;
 }

include/linux/serial_core.h

@@ -47,8 +47,8 @@
 #define PORT_U6_16550A	19	/* ST-Ericsson U6xxx internal UART */
 #define PORT_TEGRA	20	/* NVIDIA Tegra internal UART */
 #define PORT_XR17D15X	21	/* Exar XR17D15x UART */
-#define PORT_BRCM_TRUMANAGE	22
-#define PORT_MAX_8250	22	/* max port ID */
+#define PORT_BRCM_TRUMANAGE	25
+#define PORT_MAX_8250	25	/* max port ID */
 
 /*
  * ARM specific type numbers.  These are not currently guaranteed