selftests: drv-net: rss_input_xfrm: Check test prerequisites before running

Ensure the following prerequisites before executing the test:
1. 'socat' is installed on the remote host.
2. Python version supports socket.SO_INCOMING_CPU (available since v3.11).

Skip the test if either prerequisite is not met.

Reviewed-by: Nimrod Oren <[e-mail]>
Signed-off-by: Gal Pressman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/drivers/net/hw/rss_input_xfrm.py

···
     if multiprocessing.cpu_count() < 2:
         raise KsftSkipEx("Need at least two CPUs to test symmetric RSS hash")
 
+    cfg.require_cmd("socat", remote=True)
+
+    if not hasattr(socket, "SO_INCOMING_CPU"):
+        raise KsftSkipEx("socket.SO_INCOMING_CPU was added in Python 3.11")
+
     input_xfrm = cfg.ethnl.rss_get(
         {'header': {'dev-name': cfg.ifname}}).get('input_xfrm')