tls13: Use a flag not a counter for CCS and HRR handling

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index c6bb770..3e6d8d0 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -1380,7 +1380,7 @@
     MBEDTLS_SSL_DEBUG_MSG(2, ("=> write change cipher spec"));
 
     /* Only one CCS to send. */
-    if (ssl->handshake->ccs_count > 0) {
+    if (ssl->handshake->ccs_sent) {
         ret = 0;
         goto cleanup;
     }
@@ -1396,7 +1396,7 @@
     /* Dispatch message */
     MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_write_record(ssl, 0));
 
-    ssl->handshake->ccs_count++;
+    ssl->handshake->ccs_sent = 1;
 
 cleanup: