tls: fix a comment a rename a variable/symbol

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index a21b3fb..f6fd254 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4219,11 +4219,11 @@
     mbedtls_ssl_buffering_free(ssl);
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
-#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED)
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_PSA_ANY_ENABLED)
     if (handshake->xxdh_psa_privkey_is_external == 0) {
         psa_destroy_key(handshake->xxdh_psa_privkey);
     }
-#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED */
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_PSA_ANY_ENABLED */
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
     mbedtls_ssl_transform_free(handshake->transform_handshake);