Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/net/tipc/link.c b/net/tipc/link.c
index 43639ff..ebf338f 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -2471,7 +2471,7 @@
  * A pending message being re-assembled must store certain values
  * to handle subsequent fragments correctly. The following functions
  * help storing these values in unused, available fields in the
- * pending message. This makes dynamic memory allocation unecessary.
+ * pending message. This makes dynamic memory allocation unnecessary.
  */
 
 static void set_long_msg_seqno(struct sk_buff *buf, u32 seqno)