Add missing MBEDTLS_DEPRECATED_REMOVED guards

Add missing MBEDTLS_DEPRECATED_REMOVED guards around the definitions
of mbedtls_aes_decrypt and mbedtls_aes_encrypt.
This fixes the build under -Wmissing-prototypes -Werror.

Fixes #1388
diff --git a/ChangeLog b/ChangeLog
index 5f49c0b..9a61ec3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,8 @@
    * Fix the name of a DHE parameter that was accidentally changed in 2.7.0.
      Fixes #1358.
    * Fix test_suite_pk to work on 64-bit ILP32 systems. #849
+   * Don't define mbedtls_aes_decrypt and mbedtls_aes_encrypt under
+     MBEDTLS_DEPRECATED_REMOVED. #1388
 
 Changes
    * Fix tag lengths and value ranges in the documentation of CCM encryption.