hnvram: replace secure_getenv with getenv

Many of our platforms do not support support secure_getenv.

Change-Id: I1744c973d6b52413f193b2859208feecfe46d81f
diff --git a/hnvram/hnvram_main.c b/hnvram/hnvram_main.c
index 4ba0cde..e1dd780 100644
--- a/hnvram/hnvram_main.c
+++ b/hnvram/hnvram_main.c
@@ -476,7 +476,7 @@
 }
 
 int init_nvram() {
-  const char* location = secure_getenv("HNVRAM_LOCATION");
+  const char* location = getenv("HNVRAM_LOCATION");
   return (int)HMX_NVRAM_Init(location);
 }