Support parsing legacy reboot escrow data

Devices updating from R will still use the old version reboot escrow
data. We need to have the backward compatibility to avoid the one-time
failure.

Bug: 178646806
Test: atest FrameworksServicesTests:RebootEscrowDataTest;
Apply an OTA from SP1A.210114.001 to local build with fix, RoR succeeds.

Change-Id: I320966340faa80b97f79e732fb728260dfa1cee8
4 files changed