CA-141103: Do not set GRO on Linux VLAN devices

...at all. This involves removing the defaults from xcp-networkd.
The GRO settings for VLANs are inherited from the underlying physical
or bond interface.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
Merge pull request #1845 from robhoes/gro-62sp1-lcm

CLEARWATER-SP1-LCM: CA-141103: Do not set GRO on Linux VLAN devices