platform: init: Add platform_boot_dev_is_nand as WEAK function

Add platform_boot_dev_is_nand as WEAK function for targets that
do not compile boot_device.c apis.

Change-Id: I209b21a4550ce735bdd867fa37831d7070a194b9
diff --git a/platform/init.c b/platform/init.c
index f429527..46f934c 100644
--- a/platform/init.c
+++ b/platform/init.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2008 Travis Geiselbrecht
  *
- * Copyright (c) 2014-2016, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2014-2016,2019 The Linux Foundation. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files
@@ -127,6 +127,11 @@
         return 1;
 }
 
+__WEAK uint32_t platform_boot_dev_is_nand()
+{
+        return 0;
+}
+
 __WEAK uint32_t platform_get_boot_dev()
 {
         return 0;