UpdateHub Module Explicitly Disables TLS Verification

The UpdateHub module disables DTLS peer checking, which allows for a man in the middle attack. This is mitigated by firmware images requiring valid signatures. However, there is no benefit to using DTLS without the peer checking. See NCC-ZEP-018 This issue affects: zephyrproject-rtos zephyr version 2.1.0 and later versions.