Make MessageVersion constexpr

MessageVersion can be calculated at compile time, allowing for it to
be used to initialize compile-time constants.

Also ensure that we always have a return value from MessageVersion, in
case a completely unexpected value is passed as the version parameter.

Test: VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I5b06015730dc5fa6d4821a586fc17d393e530080
1 file changed