Update the default KeyMint version

As the current KeyMint version is 2 (200), reflect that in the default
XML.

Devices that ship with older KeyMint/KeyMaster version should override
the default android.hardware.hardware_keystore.xml file with the
version they support.

Test: android.keystore.cts.KeyAttestationTest#testAttestationKmVersionMatchesFeatureVersion
Bug: 222406513
Bug: 216543583
Change-Id: I6f2229019929cff747cec3907fc2a9b8ebebdcf4