HNVRAM variable GPN is not stored in binary format

By convention, a small set of HNVRAM variables are printed in hex. The
variable GPN was historically part of this set on older Broadcom
platforms, but those historical reasons don't apply to newer platforms
like Optimus.

Change-Id: I1d3c96236829d2bed6e22c745a9ab6312f7c71c8
diff --git a/commands/hnvram.c b/commands/hnvram.c
index 27ee917..8baf215 100644
--- a/commands/hnvram.c
+++ b/commands/hnvram.c
@@ -46,7 +46,6 @@
 /* these keys are stored in binary format for historical reasons */
 const char *hnvram_binary_keys[] = {
 	"LOADER_VERSION",
-	"GPN",
 	"HDCP_KEY",
 	"DTCP_KEY",
 };