[MIPS] PNX8550 build fix.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/philips/pnx8550/common/platform.c

@@ -18,6 +18,7 @@
 #include <linux/resource.h>
 #include <linux/serial.h>
 #include <linux/serial_ip3106.h>
+#include <linux/platform_device.h>
 
 #include <int.h>
 #include <usb.h>