Convert CONFIG_CMD_AES et al to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_AES
   CONFIG_AES

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Add select AES to CMD_AES]
Signed-off-by: Tom Rini <trini@konsulko.com>

lib/Kconfig

@@ -66,6 +66,17 @@ config RBTREE
 
 source lib/dhry/Kconfig
 
+menu "Security support"
+
+config AES
+	bool "Support the AES algorithm"
+	help
+	  This provides a means to encrypt and decrypt data using the AES
+	  (Advanced Encryption Standard). This algorithm uses a symetric key
+	  and is widely used as a streaming cipher. Different key lengths are
+	  supported by the algorithm but only a 128-bit key is supported at
+	  present.
+
 source lib/rsa/Kconfig
 
 config TPM
@@ -79,6 +90,8 @@ config TPM
 	  for the low-level TPM interface, but only one TPM is supported at
 	  a time by the TPM library.
 
+endmenu
+
 menu "Hashing Support"
 
 config SHA1