Print device keys in test mode

When using the rkp_factory_extraction_tool in test mode, a fake device
key is generated on the fly. This makes verifying the output difficult
as the key is permanently lost.

In test mode, print out the generated keys so that we can test if the
output data is good or not.

Test: Manually tested against backend service tooling not in AOSP
Change-Id: Ibc30044c03f5107990da6d3a03b17aa652d4b1bc
1 file changed