eth: bnxt: use context priv for struct bnxt_rss_ctx

eth: bnxt: use context priv for struct bnxt_rss_ctx

Core can allocate space for per-context driver-private data,
use it for struct bnxt_rss_ctx. Inline bnxt_alloc_rss_ctx()
at this point, most of the init (as in the actions bnxt_del_one_rss_ctx()
will undo) is open coded in bnxt_create_rxfh_context(), anyway.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20240711220713.283778-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>