[RISCV] Teach RISCVMergeBaseOffset to merge %lo into load/store folding arithmetic#185353

LiqinWeng wants to merge 1 commit intollvm:mainllvm/llvm-project:mainfrom

LiqinWeng:riscv-fold-gpLiqinWeng/llvm-project:riscv-fold-gpCopy head branch name to clipboard