clk: uniphier: add ethernet clock control support

Add clock control for ethernet controller on Pro4, PXs2, LD11 and LD20.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>