Merge branch 'fix-wrong-hds-thresh-value-setting'

Taehee Yoo says:

====================
fix wrong hds-thresh value setting

A hds-thresh value is not set correctly if input value is 0.
The cause is that ethtool_ringparam_get_cfg(), which is a internal
function that returns ringparameters from both ->get_ringparam() and
dev->cfg can't return a correct hds-thresh value.

The first patch fixes ethtool_ringparam_get_cfg() to set hds-thresh
value correcltly.

The second patch adds random test for hds-thresh value.
So that we can test 0 value for a hds-thresh properly.
====================

Link: https://patch.msgid.link/20250404122126.1555648-1-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>