net: team: Add new rx_enabled team port option

net: team: Add new rx_enabled team port option

Allow independent control over rx enablement via the rx_enabled option
without affecting tx enablement. This affects the normal enabled
option since a port is only considered enabled if both tx and rx are
enabled.

If this option is not used, then the enabled option will continue to
behave exactly as it did before.

Tested in a follow-up patch with a new selftest.

Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Marc Harvey <marcharvey@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260409-teaming-driver-internal-v7-8-f47e7589685d@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>