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/mlx4/mcg.c b/drivers/net/mlx4/mcg.c
index e71372a..279521a 100644
--- a/drivers/net/mlx4/mcg.c
+++ b/drivers/net/mlx4/mcg.c
@@ -222,7 +222,7 @@
 
 	/* the given qpn is listed as a promisc qpn
 	 * we need to add it as a duplicate to this entry
-	 * for future refernce */
+	 * for future references */
 	list_for_each_entry(dqp, &entry->duplicates, list) {
 		if (qpn == dqp->qpn)
 			return 0; /* qp is already duplicated */