Put auto-increment for IMEI2 behind a feature

Make it possible to disable the IMEI2 = (IMEI+1) fallback behaviour.
Equivalent to the `#ifndef KEYMASTER_NO_AUTO_SECOND_IMEI` in the C++
code.

Bug: 244732345
Test: VtsAidlKeyMintTargetTest
Change-Id: I89de08d1d51bedda68a10a90b975ff04178161ea
2 files changed