net: ethtool: fix get_ts_stats() documentation

net: ethtool: fix get_ts_stats() documentation

Commit 0e9c127729be ("ethtool: add interface to read Tx hardware
timestamping statistics") added documentation for timestamping
statistics, but added the detailed explanation for this method to
the get_ts_info() rather than get_ts_stats(). Move it to the correct
entry.

Cc: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1u3MTz-000Crx-IW@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>