Update mbedTLS to 2.19.3

Signed-off-by: Fabio Utzig <utzig@apache.org>
Signed-off-by: Roman Okhrimenko <roman.okhrimenko@cypress.com>
diff --git a/ext/mbedtls b/ext/mbedtls
index 04a049b..74692ae 160000
--- a/ext/mbedtls
+++ b/ext/mbedtls
@@ -1 +1 @@
-Subproject commit 04a049bda1ceca48060b57bc4bcf5203ce591421
+Subproject commit 74692aeb8c7e2c1c0f273592d87472a6f2aabacf