liquidio: use fallback for selecting txq

Remove assignment to ndo_select_queue so that fallback is used for
selecting txq.  Also remove the now-useless function that used to be
assigned to ndo_select_queue.

Signed-off-by: Satanand Burla <satananda.burla@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>