MFC r257518, r257519:

  TI sdhci driver improvements, mostly related to fdt data...

  Use the published compatible strings (our own invention, "ti,mmchs" is
  still accepted as well, for now).

  Don't blindly turn on 8-bit bus mode, because even though the controller
  supports it, the board has to be wired appropriately as well.  Use the
  published property (bus-width=<n>) and honor all the valid values (1,4,8).

  The eMMC device on a Beaglebone Black is wired for 8-bit, update the dts.

  The mmchs controller can inherently do both 1.8v and 3.0v on the first
  device and 1.8v only on other devices, unless an external transceiver is
  used.  Set the voltage automatically for the first device and honor
  the published fdt property (ti,dualvolt) for other devices.
MFC r257556:

  Arrange for uart_cpu_fdt's probe() routine to use the same table of compat
  strings as uart_bus_fdt's probe().
MFC r257557:  Add a missing register definition.
MFC r257561:

  Bugfix:  the attach routine needs to use the same table of fdt compat
  strings that the probe routine used.
MFC r257595:  Comments and style(9) only, no functional changes.
MFC r257603, r257604:

  Rename WANDBOARD-COMMON to WANDBOARD.common and adjust the configs that
  include it accordingly.  The build machinery for universe and tinderbox
  tries to build every kernel config whose name begins and ends with [A-Z0-9]
  and the common include file that has most of the options isn't buildable
  by itself, so the new lowercase .common will avoid building it.
MFC r257639:

  Remove the duplicated implementations of some bus_space functions and use
  the essentially identical generic implementations instead.  The generic
  implementations differ only in the spelling of a couple variable names
  and some formatting differences.