PXA270: Add support for multiple serial ports.

This patch adds support for multiple serial ports to the PXA target.
FFUART, BTUART and STUART are supported.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/serial.h b/include/serial.h
index f7412fd..30bfde3 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -36,6 +36,10 @@
 #endif
 
 
+extern struct serial_device serial_ffuart_device;
+extern struct serial_device serial_btuart_device;
+extern struct serial_device serial_stuart_device;
+
 extern void serial_initialize(void);
 extern void serial_devices_init(void);
 extern int serial_assign(char * name);