staging: ks7010: don't print skb->dev->name if skb is null

A null pointer dereference will occur when skb is null and
skb->dev->name is printed.  Replace the skb->dev->name with
plain text "ks_wlan" to fix this.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>