Introduce RedBox support (HSR-SAN to be more precise) for HSR networks.
Following traffic reduction optimizations have been implemented:
- Do not send HSR supervisory frames to Port C (interlink)
- Do not forward to HSR ring frames addressed to Port C
- Do not forward to Port C frames from HSR ring
- Do not send duplicate HSR frame to HSR ring when destination is Port C

The corresponding patch to modify iptable2 sources has already been sent:
https://lore.kernel.org/netdev/20240308145729.490863-1-lukma@denx.de/T/

Testing procedure (veth and netns):
-----------------------------------
One shall run:
linux-vanila/tools/testing/selftests/net/hsr/hsr_redbox.sh
(Detailed description of the setup one can find in the test
script file).

Testing procedure (real hardware):
----------------------------------
The EVB-KSZ9477 has been used for testing on net-next branch
(SHA1: 5fc68320).

Ports 4/5 were used for SW managed HSR (hsr1) as first hsr0 for ports 1/2
(with HW offloading for ksz9477) was created. Port 3 has been used as
interlink port (single USB-ETH dongle).

Configuration - RedBox (EVB-KSZ9477):
if link set lan1 down;ip link set lan2 down
ip link add name hsr0 type hsr slave1 lan1 slave2 lan2 supervision 45 version 1
ip link add name hsr1 type hsr slave1 lan4 slave2 lan5 interlink lan3 supervision 45 version 1
ip link set lan4 up;ip link set lan5 up
ip link set lan3 up
ip addr add 192.168.0.11/24 dev hsr1
ip link set hsr1 up

Configuration - DAN-H (EVB-KSZ9477):

ip link set lan1 down;ip link set lan2 down
ip link add name hsr0 type hsr slave1 lan1 slave2 lan2 supervision 45 version 1
ip link add name hsr1 type hsr slave1 lan4 slave2 lan5 supervision 45 version 1
ip link set lan4 up;ip link set lan5 up
ip addr add 192.168.0.12/24 dev hsr1
ip link set hsr1 up

This approach uses only SW based HSR devices (hsr1).

--------------          -----------------       ------------
DAN-H  Port5 | <------> | Port5         |       |
       Port4 | <------> | Port4   Port3 | <---> | PC
             |          | (RedBox)      |       | (USB-ETH)
EVB-KSZ9477  |          | EVB-KSZ9477   |       |
--------------          -----------------       ------------
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>