config: Fix typo for configuring OUTBOX_EXPIRED_TIMEOUT_MS
config: Fix typo for configuring OUTBOX_EXPIRED_TIMEOUT_MS

In esp-idf, it uses CONFIG_MQTT_OUTBOX_EXPIRED_TIMEOUT_MS rather than
CONFIG_OUTBOX_EXPIRED_TIMEOUT_MS.

Signed-off-by: Axel Lin <b6ffd6973e972cb999e8e535ab74da7fee0c035f@ingics.com>

tuanpmt/espmqtt