ARM: rmobile: Only register ethernet on V2H Blanche if not DM_ETH
If the DM_ETH is enabled, the board-specific ethernet registeration
should be disabled, make it so.
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>