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/usb/kaweth.c b/drivers/net/usb/kaweth.c
index 7dc8497..ad0298f 100644
--- a/drivers/net/usb/kaweth.c
+++ b/drivers/net/usb/kaweth.c
@@ -1221,7 +1221,7 @@
 
 	usb_set_intfdata(intf, NULL);
 	if (!kaweth) {
-		dev_warn(&intf->dev, "unregistering non-existant device\n");
+		dev_warn(&intf->dev, "unregistering non-existent device\n");
 		return;
 	}
 	netdev = kaweth->net;