mmc: sunxi: Fix mmc clocks for DM_MMC

Existing clock configure code has been followed based on the
legacy MMC dt node definitions and it cannot work with recent
dts(i) sync from Linux.

So, add clock configure code for Allwinner platforms which support
DM_MMC and eventually this will drop once CLK support is in Mainline.

Fixes: 3c92cca3 ("ARM: dts: sun4i: Update A10 dts(i) files from Linux-v4.18-rc3")
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Priit Laes <plaes@plaes.org> # Gemei G9 A10 Tablet
Tested-by: Marek Kraus <gamelasterv2@gmail.com> # A10-OLinuXino-Lime