Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/fs/befs/btree.c b/fs/befs/btree.c
index 4202db7..a66c9b1 100644
--- a/fs/befs/btree.c
+++ b/fs/befs/btree.c
@@ -5,7 +5,7 @@
  *
  * Licensed under the GNU GPL. See the file COPYING for details.
  *
- * 2002-02-05: Sergey S. Kostyliov added binary search withing
+ * 2002-02-05: Sergey S. Kostyliov added binary search within
  * 		btree nodes.
  *
  * Many thanks to: