Remove comment referencing ECDH

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index 1f498e0..256f1b1 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -2910,8 +2910,6 @@
     MBEDTLS_SSL_DEBUG_MSG(2, ("=> write server key exchange"));
 
 #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
-    /* Extract static ECDH parameters and abort if ServerKeyExchange
-     * is not needed. */
     if (mbedtls_ssl_ciphersuite_no_pfs(ciphersuite_info)) {
         /* Key exchanges not involving ephemeral keys don't use
          * ServerKeyExchange, so end here. */