Changes

contrib/saip-tool: Use repr() on security domain keys

Let's not reinvent the wheel of printing such data structures and use
the repr method provided by the respective class instead.  This also
adds the missing key_usage_qualifier information to the print-out,
as well as the mac_len of the key components.

Change-Id: Iaead4a02f07130fd00bcecc43e1c843f1c221e63