net: ethtool: mm: reset verification status when link is down

net: ethtool: mm: reset verification status when link is down

When the link partner goes down, "ethtool --show-mm" still displays
"Verification status: SUCCEEDED," reflecting a previous state that is
no longer valid.

Reset the verification status to ensure it reflects the current state.

Reviewed-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>