ssl_tls13: use PSA_WANT_ALG_ECDH as symbol for marking ECDH capability

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index cf46c2b..ad019b1 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4219,12 +4219,12 @@
     mbedtls_ssl_buffering_free(ssl);
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
-#if defined(MBEDTLS_PK_CAN_ECDH) && \
+#if defined(PSA_WANT_ALG_ECDH) && \
     (defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_SSL_PROTO_TLS1_3))
     if (handshake->ecdh_psa_privkey_is_external == 0) {
         psa_destroy_key(handshake->ecdh_psa_privkey);
     }
-#endif /* MBEDTLS_PK_CAN_ECDH && MBEDTLS_USE_PSA_CRYPTO */
+#endif /* PSA_WANT_ALG_ECDH && (MBEDTLS_USE_PSA_CRYPTO || MBEDTLS_SSL_PROTO_TLS1_3) */
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
     mbedtls_ssl_transform_free(handshake->transform_handshake);