mips: add export.h to files using EXPORT_SYMBOL/THIS_MODULE

Or else we get lots of variations on this:

arch/mips/pci/pci.c:330: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL'

scattered throughout the build.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/mips/cavium-octeon/flash_setup.c b/arch/mips/cavium-octeon/flash_setup.c
index 0ee02f5..975c203 100644
--- a/arch/mips/cavium-octeon/flash_setup.c
+++ b/arch/mips/cavium-octeon/flash_setup.c
@@ -8,6 +8,7 @@
  * Copyright (C) 2007, 2008 Cavium Networks
  */
 #include <linux/kernel.h>
+#include <linux/export.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/map.h>
 #include <linux/mtd/partitions.h>