ixgbe: use netif_<level> instead of netdev_<level>

This patch restores the ability to set msglvl through ethtool.
The issue was introduced by:
commit 849c4542

CC: Joe Perches <joe@perches.com>

Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>