mmc: sunxi: Enable the new timings for the A64 MMC controllers

The A64 MMC controllers need to set a "new timings" bit when a new rate is
set.

The actual meaning of that bit is not clear yet, but not setting it leads
to some corner-case issues, like the CMD53 failing, which is used to
implement SDIO packet aggregation.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Florian Vaussard <florian.vaussard@heig-vd.ch>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>