[llvm] [RISCV] Use bset+addi for (not (sll -1, X)). (PR #72549)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

`BSET` is expensive on both SiFive-7 (Latency = 3) and XiangShan-NanHu (Latency = 3).

https://github.com/llvm/llvm-project/pull/72549