Store TLS curve ID instead of information structure

This will reduce the number of grp ID <-> tls ID <-> curve info structs
conversions once a single EC can be hardcoded through its TLS ID.
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 8a51577..c411715 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -383,7 +383,7 @@
 #endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
 #if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
     defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
-    mbedtls_ecp_curve_info const *curve_info;  /*!< Info for EC for ECDHE. */
+    uint16_t curve_tls_id;                      /*!< TLS ID of EC for ECDHE. */
 #endif
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
     unsigned char *psk;                 /*!<  PSK from the callback         */