neighbour.h: fix comment

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
index f175212..d3ef583 100644
--- a/include/uapi/linux/neighbour.h
+++ b/include/uapi/linux/neighbour.h
@@ -58,7 +58,7 @@
 
 /* NUD_NOARP & NUD_PERMANENT are pseudostates, they never change
    and make no address resolution or NUD.
-   NUD_PERMANENT is also cannot be deleted by garbage collectors.
+   NUD_PERMANENT also cannot be deleted by garbage collectors.
  */
 
 struct nda_cacheinfo {