net: mqtt_sn: increase MQTT_SN_LIB_MAX_ADDR_SIZE to support IPv6

On IPv6, MQTT_SN_LIB_MAX_ADDR_SIZE needs to be at least 24 bytes instead
of the current 21 bytes default. Increase the default to 24 bytes so
that the MQTT-SN implementation works out of the box on IPv6.

Signed-off-by: Aurelien Jarno <[email protected]>

Author: aurel32

subsys/net/lib/mqtt_sn/Kconfig

@@ -38,7 +38,7 @@ config MQTT_SN_LIB_MAX_GATEWAYS
 
 config MQTT_SN_LIB_MAX_ADDR_SIZE
 	int "Maximum address size for the transport"
-	default 21
+	default 24
 	range 1 $(UINT8_MAX)
 	help
 	  The MQTT_SN library stores addresses internally and thus