eth: bnxt: allow deleting RSS contexts when the device is down

eth: bnxt: allow deleting RSS contexts when the device is down

Contexts get deleted from FW when the device is down, but they
are kept in SW and re-added back on open. bnxt_set_rxfh_context()
apparently does not want to deal with complexity of dealing with
both the device down and device up cases. This is perhaps acceptable
for creating new contexts, but not being able to delete contexts
makes core-driven cleanups messy. Specifically with the new RSS
API core will try to delete contexts automatically after bringing
the device down.

Support the delete-while-down case. Skip the FW logic and delete
just the driver state.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20240711220713.283778-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>