[AVR] Fix UB "left shift of negative value" detected by sanitizer

Introduced by 1793fa8.

Author: s-barannikov

llvm/lib/Target/AVR/Disassembler/AVRDisassembler.cpp

@@ -110,15 +110,15 @@ static DecodeStatus decodeRelCondBrTarget7(MCInst &Inst, unsigned Field,
                                            uint64_t Address,
                                            const MCDisassembler *Decoder) {
   // The legal range is [-128, 126] (in bytes).
-  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 7) << 1));
+  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 7) * 2));
   return MCDisassembler::Success;
 }
 
 static DecodeStatus decodeRelCondBrTarget13(MCInst &Inst, unsigned Field,
                                             uint64_t Address,
                                             const MCDisassembler *Decoder) {
   // The legal range is [-4096, 4094] (in bytes).
-  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 12) << 1));
+  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 12) * 2));
   return MCDisassembler::Success;
 }