Fix misspellings of "system", "controller", "interrupt" and "necessary".

Fix the various misspellings of "system", controller", "interrupt" and
"[un]necessary".

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 57adfe9..98c3781 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -319,7 +319,7 @@
 
 /* to protect file being unlinked from getting lost we "safe" link files
    being unlinked. This link will be deleted in the same transaction with last
-   item of file. mounting the filesytem we scan all these links and remove
+   item of file. mounting the filesystem we scan all these links and remove
    files which almost got lost */
 void add_save_link(struct reiserfs_transaction_handle *th,
 		   struct inode *inode, int truncate)