Add sigalg types to x509_crt.c

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/library/x509_crt.c b/library/x509_crt.c
index ed85d06..dca4679 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -2126,7 +2126,7 @@
     }
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    if (rs_ctx != NULL && child->sig_pk == MBEDTLS_PK_ECDSA) {
+    if (rs_ctx != NULL && child->sig_pk == MBEDTLS_PK_SIGALG_ECDSA) {
         return mbedtls_pk_verify_restartable(&parent->pk,
                                              child->sig_md, hash, hash_len,
                                              child->sig.p, child->sig.len, &rs_ctx->pk);