net: fjes: use ethtool string helpersThe latter is the preferred way to copy ethtool strings.Avoids manually incrementing the pointer.Signed-off-by: Rosen Penev <rosenp@gmail.com>Reviewed-by: Simon Horman <horms@kernel.org>Link: https://patch.msgid.link/20241029232721.8442-1-rosenp@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>