[RISCV] Address review comment from 88062

As pointed out by Fraser, KillSrcReg is always false at this point in
code, and having the inconcistency on whether we check the flag between
the if and else blocks is confusing.

llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp

@@ -210,8 +210,7 @@ void RISCVRegisterInfo::adjustReg(MachineBasicBlock &MBB,
       unsigned Opc = NumOfVReg == 2 ? RISCV::SH1ADD :
         (NumOfVReg == 4 ? RISCV::SH2ADD : RISCV::SH3ADD);
       BuildMI(MBB, II, DL, TII->get(Opc), DestReg)
-          .addReg(ScratchReg, RegState::Kill)
-          .addReg(SrcReg, getKillRegState(KillSrcReg))
+          .addReg(ScratchReg, RegState::Kill).addReg(SrcReg)
           .setMIFlag(Flag);
     } else {
       TII->mulImm(MF, MBB, II, DL, ScratchReg, NumOfVReg, Flag);