Fix qemu_free use in nand.c

nand.c is using free() instead of qemu_free().
Fix it.

Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/nand.c b/hw/nand.c
index 37fd524..838f8bc 100644
--- a/hw/nand.c
+++ b/hw/nand.c
@@ -507,9 +507,9 @@
     }
 
     if (!s->bdrv || s->mem_oob)
-        free(s->storage);
+        qemu_free(s->storage);
 
-    free(s);
+    qemu_free(s);
 }
 
 #else