net: sh_eth: Add DM and DT support

Add DM capable code into the SH ethernet driver and support probing
both from DT and pdata. The legacy non-DM, non-DT support is retained
as there are still systems in the tree which are not DM or DT capable.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Joe Hershberger <joe.hershberger@ni.com>