or1k: Remove 64-bit support, it's not used and it breaks 32-bit hosts
Reported by Rich Felker when building on 32-bit hosts. Backwards jump
negative offsets were not calculated correctly due to improper 32-bit
to 64-bit zero-extension. The 64-bit fields are present because we
are mixing 32-bit and 64-bit architectures in our cpu descriptions.
Removing 64-bit fixes the issue. We don't use 64-bit, there is an architecture
spec for 64-bit but no implementations or simulators. My thought is if
we need them in the future we should do the proper work to support both
32-bit and 64-bit implementations co-existing then.