net: mtk_eth_soc: use ethtool_puts

Allows simplifying get_strings and avoids manual pointer manipulation.

Tested on Belkin RT1800.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Link: https://patch.msgid.link/20241011200225.7403-1-rosenp@gmail.com


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