reset: uniphier: add ethernet reset control support

Add reset lines for ethernet controller on Pro4, PXs2, LD11 and
LD20 SoCs.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>