stoken: move to Encryption submenu

Part of a wider housekeeping effort on the packages repository.

Signed-off-by: Alberto Bursi <alberto.bursi@outlook.it>

utils/stoken/Makefile

@@ -38,6 +38,7 @@ define Package/stoken
   $(call Package/stoken/Default)
   SECTION:=utils
   CATEGORY:=Utilities
+  SUBMENU:=Encryption
   DEPENDS:=+libstoken
   MENU:=1
 endef