[SERIAL] Use an enum for serial8250 platform device IDs

Rather than hard-coding the platform device IDs, enumerate them.
We don't particularly care about the actual ID we get, just as
long as they're unique.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/linux/serial_8250.h

@@ -29,6 +29,21 @@ struct plat_serial8250_port {
 	unsigned int	flags;		/* UPF_* flags */
 };
 
+/*
+ * Allocate 8250 platform device IDs.  Nothing is implied by
+ * the numbering here, except for the legacy entry being -1.
+ */
+enum {
+	PLAT8250_DEV_LEGACY = -1,
+	PLAT8250_DEV_PLATFORM,
+	PLAT8250_DEV_PLATFORM1,
+	PLAT8250_DEV_FOURPORT,
+	PLAT8250_DEV_ACCENT,
+	PLAT8250_DEV_BOCA,
+	PLAT8250_DEV_HUB6,
+	PLAT8250_DEV_MCA,
+};
+
 /*
  * This should be used by drivers which want to register
  * their own 8250 ports without registering their own