KeyMint: version gate attestation of IMEI2

aosp/3106417 added extra tests with for device ID attestation, but
didn't include a version gate for attesting to the second IMEI value,
which is only present in KeyMint v3+.

Test: VtsAidlKeyMintTargetTest
Change-Id: I95f47942058781709efe96d38442e0518e39705d