Fix attestation properties reading logic

Fixed the logic of reading attestation specific properties in
Build.java.

Bug: 110779648
Test: atest CtsKeystoreTestCases:android.keystore.cts.KeyAttestationTest CtsKeystoreTestCases:DeviceOwnerKeyManagementTest
Change-Id: I9af7daa08cbd8bb52f3509fe93f787ba94b7bbc3
1 file changed