[RISCV][NFC] Simplify PatFrag mul_const_oneuse

[craig.topper]

LGTM

llvm/lib/Target/RISCV/RISCVInstrInfo.td

 
 def and_oneuse : binop_oneuse<and>;
 def add_oneuse : binop_oneuse<add>;
 def mul_oneuse : binop_oneuse<mul>;
 
 def mul_const_oneuse : PatFrag<(ops node:$A, node:$B),
                                (mul node:$A, node:$B), [{
   if (auto *N1C = dyn_cast<ConstantSDNode>(N->getOperand(1)))
-    if (N1C->hasOneUse())
-      return true;
+    return N1C->hasOneUse();
   return false;
 }]>;
 
 class unop_oneuse<SDPatternOperator operator>
     : PatFrag<(ops node:$A),
               (operator node:$A), [{
   return N->hasOneUse();
 }]>;