ixgbe: fix for real_num_tx_queues update issue

Currently netdev_features_change is called before fcoe tx queues
setup is done, so this patch moves calling of netdev_features_change
after tx queues setup is done in ixgbe_init_interrupt_scheme, so
that real_num_tx_queues is updated correctly on each fcoe enable
or disable.

This allows additional fcoe queues updated correctly in vlan driver
for their correct queue selection.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>