selftests: drv-net: rss_ctx: add identifier to traffic comments

Include the "name" of the context in the comment for traffic
checks. Makes it easier to reason about which context failed
when we loop over 32 contexts (it may matter if we failed in
first vs last, for example).

Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>