selftest: net-drv: hds: add test for HDS feature

selftest: net-drv: hds: add test for HDS feature

HDS/HDS-thresh features were updated/implemented. so add some tests for
these features.

HDS tests are the same with `ethtool -G eth0 tcp-data-split <on | off |
auto >` but `auto` depends on driver specification.
So, it doesn't include `auto` case.

HDS-thresh tests are same with `ethtool -G eth0 hds-thresh <0 - MAX>`
It includes both 0 and MAX cases. It also includes exceed case, MAX + 1.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20250114142852.3364986-11-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>