recipes: remove offload setting for non-existing device in vland over bond test

Fix for 3_vlans_over_bond.py task that was requesting non existing
device causing an exception. Machine 'm2' has only one ethernet device.

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
recipes: fix description of vlan over bond tests

Match README files to recipe xmls.

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>