net: enable RPS on vlan devices

net: enable RPS on vlan devices

This patch modifies the RPS processing code so that it searches
for a matching vlan interface on the packet and then uses the
RPS settings of the vlan interface.  If no vlan interface
is found or the vlan interface does not have RPS enabled,
it will fall back to the RPS settings of the underlying device.

In supporting VMs where we can't control the OS being used,
we'd like to separate the VM cpu processing from the host's
cpus as a way to help mitigate the impact of the L1TF issue.
When running the VM's traffic on a vlan we can stick the Rx
processing on one set of CPUs separate from the VM's CPUs.
Yes, choosing to use this will cause a bit of throughput pain
when the packets are actually passed into the VM and have to
move from one cache to another.

Orabug: 28645929

Signed-off-by: Silviu Smarandache <silviu.smarandache@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>