ssl_misc: fix guards for PSA data used in XXDH key exchanges

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index fedbb95..0139e55 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4219,13 +4219,11 @@
     mbedtls_ssl_buffering_free(ssl);
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
-#if (defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)) && \
-    (defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_SSL_PROTO_TLS1_3))
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED)
     if (handshake->xxdh_psa_privkey_is_external == 0) {
         psa_destroy_key(handshake->xxdh_psa_privkey);
     }
-#endif /* (PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH) &&
-          (MBEDTLS_USE_PSA_CRYPTO || MBEDTLS_SSL_PROTO_TLS1_3) */
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED */
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
     mbedtls_ssl_transform_free(handshake->transform_handshake);