mlx4: Call alloc_etherdev to allocate RX and TX queues

Changed driver to call alloc_etherdev_mqs so that the number of TX
and RX queues can be set to correct values in the netdev device.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>