Add code improvments and refactoring in dealing with ALPN

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index b05bfe1..57d7bc6 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1305,7 +1305,8 @@
 #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION && MBEDTLS_SSL_CLI_C */
 
 #if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN) && defined(MBEDTLS_SSL_SRV_C)
-    char *ticket_alpn;                      /*!< ALPN negotiated in the session */
+    char *ticket_alpn;                      /*!< ALPN negotiated in the session
+                                                 during which the ticket was generated. */
 #endif
 
 #if defined(MBEDTLS_HAVE_TIME) && defined(MBEDTLS_SSL_CLI_C)