Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 9f6d670..4609bc0 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -1448,7 +1448,7 @@
 
 		/*
 		 *check if we are on the last channel or
-		 *we exceded the lenght of the data to
+		 *we exceded the length of the data to
 		 *fragment
 		 */
 		if ((nfree <= 0) || (flen > len))