selftests: drv-net: rss: Add retries to test_rss_key_indir to reduce flakes

selftests: drv-net: rss: Add retries to test_rss_key_indir to reduce flakes

The test generates 16 flows, and verifies that traffic is distributed
across two queues via the NICs RSS indirection table. The likelihood of the
flows skewing to a single queue is high, so we retry sending traffic up to
3 times.

Alternatively, we could increase the number of generated flows. But
debug kernels may struggle to ramp this many flows.

During manual testing, the test passed for 10,000 consecutive runs.

Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1@gmail.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20260309204215.2110486-1-dimitri.daskalakis1@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>