ARM: dts: sun8i: Add mmc clocks to the dtsi

The MMC module clocks on sun8i are the same as those found on
previous Allwinner SoCs, module 0 clocks.

This patch adds the clocks nodes to the dtsi with existing drivers.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>