readline: remove intermediate variable

This commit removes an extrea intermediate variable. This
makes the call consistent with other uses of validateUint32()
in the codebase.

PR-URL: #31676
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/readline.js

@@ -123,8 +123,7 @@ function Interface(input, output, completer, terminal) {
     terminal = input.terminal;
     historySize = input.historySize;
     if (input.tabSize !== undefined) {
-      const positive = true;
-      validateUint32(input.tabSize, 'tabSize', positive);
+      validateUint32(input.tabSize, 'tabSize', true);
       this.tabSize = input.tabSize;
     }
     removeHistoryDuplicates = input.removeHistoryDuplicates;