[flang][intrinsics] NFC: make comment consistent (llvm#133972)

Just makes this named argument comment consistent with all the others in
the file.

Author: akuhlens

flang/lib/Optimizer/Builder/IntrinsicCall.cpp

@@ -756,7 +756,7 @@ static constexpr IntrinsicHandler handlers[]{
     {"perror",
      &I::genPerror,
      {{{"string", asBox}}},
-     /*isElemental*/ false},
+     /*isElemental=*/false},
     {"popcnt", &I::genPopcnt},
     {"poppar", &I::genPoppar},
     {"present",