Support for Technicolor CGA2121

[MightyFilipns]

Adds support for the decryption of GatewatySettings.bin from CGA2121. Encryption is not yet implemented.

The profile must be specified using the -P option, otherwise, the Generic profile will be used. This is because the generic profile uses the same checksum salt as CGA2121, which is used to automatically identify the profile.

When decrypting, the password must be specified, which is the modem's CM MAC address in lowercase hex colon format (xx:xx:xx:xx:xx:xx).