selftests: hsr: Add tests for faulty links

selftests: hsr: Add tests for faulty links

Add a test case that can support different types of faulty links for all
protocol versions (HSRv0, HSRv1, PRPv1). It starts with a baseline with
fully functional links. The first faulty case is one link being cut during
the ping. This test uses a different function for ping that sends more
packets in shorter intervals to stress the duplicate detection algorithms a
bit more and allow for future tests with other link faults (packet loss,
reordering, etc.).

As the link fault tests now cover the cut link for HSR and PRP, it can be
removed from the hsr_ping test. Note that the removed cut link test did not
really test the fault because do_ping_long takes about 1sec while the link
is only cut after a 3sec sleep.

Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/dad52276e2c349ecb96168bef7e3001bf7becc81.1770299429.git.fmaurer@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>