ixgbe: remove dead code

The question around getting rid of the assignments seems lived
long enough, if they are not needed until now, we can drop them.

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>

Approved by: imp
Obtained from: DPDK (a6395d471e14e5a7432875dad8fb3533238c5167)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D31621