env: Migrate CONFIG_ENV_AES to Kconfig and deprecate

The underlying implementation for ENV_AES has security complications and
is not recommended for use.  Please see CVE-2017-3225 and CVE-2017-3226
for more details.  Mark this as deprecated now and delete this in the
medium term if no one comes forward to re-work the support.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/env/Kconfig b/env/Kconfig
index f12ef28..024d4d7 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -375,6 +375,14 @@
 
 endchoice
 
+config ENV_AES
+	bool "AES-128 encryption for stored environment (DEPRECATED)"
+	help
+	  Enable this to have the on-device stored environment be encrypted
+	  with AES-128.  The implementation here however has security
+	  complications and is not recommended for use.  Please see
+	  CVE-2017-3225 and CVE-2017-3226 for more details.
+
 config ENV_FAT_INTERFACE
 	string "Name of the block device for the environment"
 	depends on ENV_IS_IN_FAT