Revert "[NVPTX] Improve lowering of v2i16 logical ops. (#67073)"

This reverts commit 64857900.

Caused xla/tests:float8_test_gpu to fail
```
LLVM ERROR: Cannot select: t118: v2i16 = or t375, t401
  t375: v2i16 = BUILD_VECTOR t374, t372
    t374: i16 = select t247, Constant:i16<8960>, t360
      t247: i1 = setcc t199, Constant:i16<7>, seteq:ch
        t199: i16 = extract_vector_elt t187, Constant:i64<0>
          t187: v2i16 = and t183, t410
            t183: v2i16 = BUILD_VECTOR t383, t384
            ...
```

Acked by author to revert