mmc: add MMC_QUIRK_DISABLE_CD

006ebd5d introduced sdio_disable_cd(), which disconnects the pull-up
resistor on CD/DAT[3] (pin 1) of the card.

Make it possible to start using sdio_disable_cd() by introducing
MMC_QUIRK_DISABLE_CD.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Chris Ball <cjb@laptop.org>