This change modifies the sdhci driver as follows:

  - drops unused SDMA code (the new controllers use ADMA, niot yet
    implemented).
  - modify structure names to match changes in depthcharge (camal case
    instead of underscores)
  - make new structure names match depthcharge coding style
  - account for different device/controllir/interface structures
    encapsulation
  - use modified constant names
  - bring in from u-boot a few missing functions
  - account for different driver API (add sdhci_update())

This also adds a wrapper which discovers the PCI devices and calls
the SDHCI entry point with it. This in fact violates depthcharge
convention which requires that new_host...() functions do not touch
hardware. This will be modified in an upcoming CL.

BUG=chrome-os-partner:22580
TEST=manual
  . with these changes, the upcoming board file change and a test
    modification of the main() function, the eMMC device gets
    initialized and allows to read the first sector of the kernel.

Change-Id: I1ace24f0f4befe139670bb5d68b22104b489301d
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/175164


Reviewed-by: Hung-Te Lin <hungte@chromium.org>