net: team: Add new tx_enabled team port option

net: team: Add new tx_enabled team port option

This option allows independent control over tx enablement without
affecting rx enablement. Like the rx_enabled option, this also
implicitly affects the enabled option.

If this option is not used, then the enabled option will continue to
behave 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-v7-9-f47e7589685d@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>