Squashed commit upgrading to mbedtls-2.28.1

Squash merging branch import/mbedtls-2.28.1

 ebf1f6a58089 ("libmbedtls: compile new files added with 2.28.1")
 3ffb51b58a54 ("libmbedtls: add SM2 curve")
 c425755720b4 ("libmbedtls: mbedtls_mpi_exp_mod(): optimize mempool usage")
 23493c822a82 ("libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage")
 dcdca2348dff ("libmbedtls: mbedtls_mpi_exp_mod() initialize W")
 dc2994976958 ("libmbedtls: fix no CRT issue")
 c6628873b281 ("libmbedtls: add interfaces in mbedtls for context memory operation")
 8acd202d3e55 ("libmedtls: mpi_miller_rabin: increase count limit")
 37284e28d5d9 ("libmbedtls: add mbedtls_mpi_init_mempool()")
 b499a75f29f3 ("libmbedtls: make mbedtls_mpi_mont*() available")
 2080a8c96a5d ("mbedtls: configure mbedtls to reach for config")
 e0858334327a ("mbedtls: remove default include/mbedtls/config.h")
 dd9688e6b8ce ("Import mbedtls-2.28.1")

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/ssl_ticket.c b/lib/libmbedtls/mbedtls/library/ssl_ticket.c
index 626d137..e0126cc 100644
--- a/lib/libmbedtls/mbedtls/library/ssl_ticket.c
+++ b/lib/libmbedtls/mbedtls/library/ssl_ticket.c
@@ -37,7 +37,7 @@
 #include <string.h>
 
 /*
- * Initialze context
+ * Initialize context
  */
 void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx )
 {
@@ -66,6 +66,7 @@
 /*
  * Generate/update a key
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx,
                                unsigned char index )
 {
@@ -96,6 +97,7 @@
 /*
  * Rotate/generate keys if necessary
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_ticket_update_keys( mbedtls_ssl_ticket_context *ctx )
 {
 #if !defined(MBEDTLS_HAVE_TIME)
@@ -245,8 +247,7 @@
     {
          goto cleanup;
     }
-    state_len_bytes[0] = ( clear_len >> 8 ) & 0xff;
-    state_len_bytes[1] = ( clear_len      ) & 0xff;
+    MBEDTLS_PUT_UINT16_BE( clear_len, state_len_bytes, 0 );
 
     /* Encrypt and authenticate */
     if( ( ret = mbedtls_cipher_auth_encrypt_ext( &key->ctx,