[RISCV] Don't check haveNoCommonBitsSet in RISCVGatherScatterLowering

If an or instruction has no common bits set in its operands, InstCombine will
set the disjoint flag. This means we shouldn't need to compute it ourselves
anymore in RISCVGatherScatterLowering, and can just rely on said flag being
set.
Originally split out from #77800

Author: lukel97

llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp

@@ -250,8 +250,7 @@ bool RISCVGatherScatterLowering::matchStridedRecurrence(Value *Index, Loop *L,
     return false;
   case Instruction::Or:
     // We need to be able to treat Or as Add.
-    if (!haveNoCommonBitsSet(BO->getOperand(0), BO->getOperand(1), *DL) &&
-        !cast<PossiblyDisjointInst>(BO)->isDisjoint())
+    if (!cast<PossiblyDisjointInst>(BO)->isDisjoint())
       return false;
     break;
   case Instruction::Add: