Merge branch 'enhance-network-interface-feature-testing'

Abhinav Jain says:

====================
Enhance network interface feature testing

This small series includes fixes for creation of veth pairs for
networkless kernels & adds tests for turning the different network
interface features on and off in selftests/net/netdevice.sh script.
Tested using vng and compiles for network as well as networkless kernel.

   # selftests: net: netdevice.sh
   # No valid network device found, creating veth pair
   # PASS: veth0: set interface up
   # PASS: veth0: set MAC address
   # XFAIL: veth0: set IP address unsupported for veth*
   # PASS: veth0: ethtool list features
   # PASS: veth0: Turned off feature: rx-checksumming
   # PASS: veth0: Turned on feature: rx-checksumming
   # PASS: veth0: Restore feature rx-checksumming to initial state on
   # Actual changes:
   # tx-checksum-ip-generic: off

   ...

   # PASS: veth0: Turned on feature: rx-udp-gro-forwarding
   # PASS: veth0: Restore feature rx-udp-gro-forwarding to initial state off
   # Cannot get register dump: Operation not supported
   # XFAIL: veth0: ethtool dump not supported
   # PASS: veth0: ethtool stats
   # PASS: veth0: stop interface
====================

Link: https://patch.msgid.link/20240821171903.118324-1-jain.abhinav177@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>