Fix undeclared symbol warnings from sparse

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5539 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/hw/nand.c b/hw/nand.c
index 294a83f..11f8efc 100644
--- a/hw/nand.c
+++ b/hw/nand.c
@@ -106,7 +106,7 @@
 # include "nand.c"
 
 /* Information based on Linux drivers/mtd/nand/nand_ids.c */
-struct nand_info_s {
+static const struct nand_info_s {
     int size;
     int width;
     int page_shift;