examples/mqttc: add option to use MBED TLS for connections

Signed-off-by: Petro Karashchenko <petro.karashchenko@gmail.com>

Author: pkarashchenko

examples/mqttc/Kconfig

@@ -6,7 +6,7 @@
 config EXAMPLES_MQTTC
 	tristate "Enable MQTT-C Example"
 	default n
-	depends on NETUTILS_MQTTC && !NETUTILS_MQTTC_WITH_MBEDTLS
+	depends on NETUTILS_MQTTC
 	---help---
 		Enable a simple MQTT-C publisher example
 
@@ -28,4 +28,12 @@ config EXAMPLES_MQTTC_RXSIZE
 	int "RX Buffer size"
 	default 256
 
+config EXAMPLES_MQTTC_ALLOW_UNVERIFIED_TLS
+	bool "Allow unverified TLS"
+	default n
+	---help---
+		Do not fail TLS connection if certificate verification fails. Usually
+		this is useful during development when connection to server with
+		self-signed certificates
+
 endif