Revert "X86InstrInfo: Support immediates that are +1/-1 different in optimizeCompareInstr"

This casued miscompiles of switches, see comments on the code review.

> This extends `optimizeCompareInstr` to re-use previous comparison
> results if the previous comparison was with an immediate that was 1
> bigger or smaller. Example:
>
>     CMP x, 13
>     ...
>     CMP x, 12   ; can be removed if we change the SETg
>     SETg ...    ; x > 12  changed to `SETge` (x >= 13) removing CMP
>
> Motivation: This often happens because SelectionDAG canonicalization
> tends to add/subtract 1 often when optimizing for fallthrough blocks.
> Example for `x > C` the fallthrough optimization switches true/false
> blocks with `!(x > C)` --> `x <= C` and canonicalization turns this into
> `x < C + 1`.
>
> Differential Revision: https://reviews.llvm.org/D110867

This reverts commit e2c7ee07.