Properly define the constant for requesting the use of device individual
attestation certificate and use it in AttestationUtils.
This lets callers to DevicePolicyManager.generateKeyPair request the use
of device-unique attestation certificate, on Keymaster implementations
that support this.
Bug: 140193672
Bug: 136494773
Test: atest com.android.cts.devicepolicy.MixedDeviceOwnerTest#testKeyManagement
Change-Id: I74de89e4c121a27b0495dcb99b0775445c3d4eaf