update based on comments.

Signed-off-by: Xiaofei Bai <xiaofei.bai@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 1db6202..c2ce077 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -809,10 +809,9 @@
                                              represents an extension and defined
                                              as \c MBEDTLS_SSL_EXT_XXX */
 
-#if defined(MBEDTLS_ECDSA_C)
-    unsigned char cert_req_ctx_len;     /*!< certificate request context
-                                             length */
-    unsigned char* cert_req_ctx;        /*!< certificate request context */
+#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+    unsigned char certificate_request_context_len;
+    unsigned char *certificate_request_context;
 #endif
 
     union