sh_eth: Use dev_err_probe() helper

Use the dev_err_probe() helper, instead of open-coding the same
operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/2576cc15bdbb5be636640f491bcc087a334e2c02.1638959463.git.geert+renesas@glider.be
Signed-off-by: Jakub Kicinski <kuba@kernel.org>