eth: otx2: migrate to the *_rxfh_context ops

eth: otx2: migrate to the *_rxfh_context ops

otx2 only supports additional indirection tables (no separate keys
etc.) so the conversion to dedicated callbacks and core-allocated
context is mostly removing the code which stores the extra tables
in the driver. Core already stores the indirection tables for
additional contexts, and doesn't call .get for them.

One subtle change here is that we'll now start with the table
covering all queues, not directing all traffic to queue 0.
This is what core expects if the user doesn't pass the initial
indir table explicitly (there's a WARN_ON() in the core trying
to make sure driver authors don't forget to populate ctx to
defaults).

Drivers implementing .create_rxfh_context don't have to set
cap_rss_ctx_supported, so remove it.

Tested-by: Geetha Sowjanya <gakula@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250707184115.2285277-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>