tree-wide: fix 'lenght' typo in comments and code

Some misspelled occurences of 'octet' and some comments were also fixed
as I was on it.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/isdn/mISDN/l1oip_core.c b/drivers/isdn/mISDN/l1oip_core.c
index 0843fcf..325b1ad 100644
--- a/drivers/isdn/mISDN/l1oip_core.c
+++ b/drivers/isdn/mISDN/l1oip_core.c
@@ -477,7 +477,7 @@
 		printk(KERN_DEBUG "%s: received frame, parsing... (%d)\n",
 			__func__, len);
 
-	/* check lenght */
+	/* check length */
 	if (len < 1+1+2) {
 		printk(KERN_WARNING "%s: packet error - length %d below "
 			"4 bytes\n", __func__, len);