Add AES feature unavailable error code
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index b5560cc..660ec2a 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -38,6 +38,7 @@
#define MBEDTLS_ERR_AES_INVALID_KEY_LENGTH -0x0020 /**< Invalid key length. */
#define MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH -0x0022 /**< Invalid data input length. */
+#define MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE -0x006E /**< Feature not available, e.g. unsupported AES key size. */
#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
!defined(inline) && !defined(__cplusplus)