mmc: sdhci-omap: Add special reset capability

Some omap controllers need software to monitor a 0->1->0 for software
reset. Add a SDHCI_OMAP_SPECIAL_RESET flag to indicate this.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200116105154.7685-11-faiz_abbas@ti.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>