mmc: use .multi_io_quirk on sh_mobile

Now, sh_mobile_sdhi can use .multi_io_quirk callback
instead of MMC_CAP2_NO_MULTI_READ flags.
let's use it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>