OMAP: Zoom2: update serial platform_data id for external UART

Now that on-chip UARTs each have separate platform_data, the external
UART needs an non-conflicting ID.  Since there are 3 on-chip UARTs,
the Zoom2 external UART will be registered after as the fourth.
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-omap2/board-zoom-debugboard.c

@@ -96,7 +96,7 @@ static struct plat_serial8250_port serial_platform_data[] = {
 
 static struct platform_device zoom2_debugboard_serial_device = {
 	.name			= "serial8250",
-	.id			= PLAT8250_DEV_PLATFORM1,
+	.id			= 3,
 	.dev			= {
 		.platform_data	= serial_platform_data,
 	},