mmc: sdhci: add ability to stay runtime-resumed if the card is powered up

If card power is dependent on SD bus power then the host controller
must not be runtime suspended while the card is powered up.  Add
the ability to stay runtime-resumed in that case and enable it with a new
quirk SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>