tty: Fix typo in tty drivers

Correct spelling typo in debug messages within tty drivers.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index 0d2ea0c..a4f488f 100644
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -178,7 +178,7 @@
 		proto = HV_PROTOCOL_HVSI;
 		ops = &hvc_opal_hvsi_ops;
 	} else {
-		pr_err("hvc_opal: Unkown protocol for %s\n",
+		pr_err("hvc_opal: Unknown protocol for %s\n",
 		       dev->dev.of_node->full_name);
 		return -ENXIO;
 	}