Add a driver for SDHCI controllers enumerated via ACPI and identified
by the ACPI Compatibility ID PNP0D40 (or other SDHCI-specific ACPI
hardware IDs in the future).

[rjw: Added the changelog.]
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Acked-by: NChris Ball <cjb@laptop.org>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>