net: core: Make netif_wake_subqueue a wrapper

netif_wake_subqueue() is duplicating the same thing that netif_tx_wake_queue()
does, so make it call it directly after looking up the queue from the index.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>