net: Add Padding for Alignment in Axxia FEMAC

commit 40422ce2bb86cbb4b5be534a6d54502fb78c6df7 from
https://github.com/axxia/linux-yocto.git

 v5.10/standard/axxia-dev/base.

Padding for alignment was short 2 bytes after aligning to
16 bytes in the receive path.

Signed-off-by: John Jacques <john.jacques@intel.com>
Signed-off-by: Liwei Song <liwei.song@windriver.com>