fix comment issue

Co-authored-by: Xiaokang Qian <53458466+xkqian@users.noreply.github.com>
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 84b6b80..7c28c57 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -61,7 +61,7 @@
     size_t ke_modes_len;
     int ke_modes = 0;
 
-    /* Read PSK mode list length (1 Byte) */
+    /* Read ke_modes length (1 Byte) */
     MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 );
     ke_modes_len = *p++;
     /* Currently, there are only two PSK modes, so even without looking