mmc: core: fix the decision of HS200/DDR card-type

Current implementation decides the card type exclusively. Even though
eMMC device can support both HS200 and DDR mode, card type will be
set only for HS200. If the host doesn't support HS200 but has DDR
capability, then DDR mode can't be selected.

Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Chris Ball <cjb@laptop.org>