[FIR] Minor. Fix code style

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirArgumentsToParametersMapper.kt

@@ -118,16 +118,16 @@ private class FirCallArgumentsProcessor(private val function: FirFunction<*>) {
             return false
         }
 
-        if (!parameter.isVararg) {
+        return if (!parameter.isVararg) {
             currentPositionedParameterIndex++
 
             result[parameter] = ResolvedCallArgument.SimpleArgument(argument)
-            return false
+            false
         }
         // all position arguments will be mapped to current vararg parameter
         else {
             addVarargArgument(argument)
-            return true
+            true
         }
     }