mmc: core: Enable tuning according to the actual timing

While in sdhci_execute_tuning() the choice whether or not to enable the
tuning is done on the actual timing, in the mmc_sdio_init_uhs_card() the
check is done on the capability of the card.

This difference is causing some issues with some SDIO cards in DDR50
mode where the CDM19 is wrongly issued.

With this patch we modify the check in both
mmc_(sd|sdio)_init_uhs_card() functions to take the proper decision
only according to the actual timing specification.

Cc: stable@vger.kernel.org
Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>