As per following suggestion from Dean Long on PR https://github.com/openjdk/jdk/pull/24664

"This looks OK, but we could do better. Instead of making the relocation point to the end of the instruction and then looking up the offset with patch_barrier_relocation_offset(), why not make the offset always 0 and have the relocation point to the data offset inside the instruction"

We can fold the offset into relocation and simplify the existing scheme.