net: thunderbolt: Enable end-to-end flow control also in transmit

According to USB4 specification, if E2E flow control is disabled for
the Transmit Descriptor Ring, the Host Interface Adapter Layer shall
not require any credits to be available before transmitting a Tunneled
Packet from this Transmit Descriptor Ring, so e2e flow control should
be enabled in both directions.

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/20250624153805.GC2824380@black.fi.intel.com


Signed-off-by: zhangjianrong <zhangjianrong5@huawei.com>
Link: https://patch.msgid.link/20250628093813.647005-1-zhangjianrong5@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>