net: atlantic: use ethtool_sprintf

Allows simplifying get_strings and avoids manual pointer manipulation.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20240807190303.6143-1-rosenp@gmail.com


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