classifier: Fix typo in comment.
*
* The classifier may safely be accessed by many reader threads concurrently
* and by a single writer, or by multiple writers when they guarantee mutually
- * exlucive access to classifier modifications.
+ * exclusive access to classifier modifications.
*
* Since the classifier rules are RCU protected, the rule destruction after
* removal from the classifier must be RCU postponed. Also, when versioning is
