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/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index df0b853..df25ecc 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -773,7 +773,7 @@
 	      getChild:
 		/* update max. number of pages to split */
 		if (BT_STACK_FULL(btstack)) {
-			/* Something's corrupted, mark filesytem dirty so
+			/* Something's corrupted, mark filesystem dirty so
 			 * chkdsk will fix it.
 			 */
 			jfs_error(sb, "stack overrun in dtSearch!");