rose: device refcount leak

While hunting dev_put() for net-next-2.6, I found a device refcount
leak in ROSE, ioctl(SIOCADDRT) error path.

Fix is to not touch device refcount, as we hold RTNL

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>