MFC r261938, r261939, r261940, r261944, r261945, r261946, r261947, r261956, r261957...

MFC r261938, r261939, r261940, r261944, r261945, r261946, r261947, r261956, r261957, r261983, r261094,
    r261955, r261958,

  Add a driver to provide access to imx6 on-chip one-time-programmble data.

  Make it possible to access the ocotp registers before the ocotp device
  is attached, by establishing a temporary mapping of the registers when
  necessary.

  It turns out Freescale cleverly made the ocotp device compatible across
  several different families of SoCs, so move it to the freescale directory
  and prefix everything with fsl rather than imx6.

  Convert the imx6 sdhci "R1B fix" from a busy-loop in the interrupt handler
  to a callout.

  Increase the wait time for acquiring the SD bus from 10 to 250ms.

  If no compatible cards were found after probing the SD bus, say so.

  Add timeout logic to sdhci, separate from the timeouts done by the hardware.

  After a timeout, reset the controller using SDHCI_RESET_CMD|SDHCI_RESET_DATA
  rather than SDHCI_RESET_ALL; the latter turns off clocks and power, removing
  any possibility of recovering from the error.

  Add a helper routine to depth-search the device tree for a node with a
  matching 'compatible' property.

git-svn-id: svn://svn.freebsd.org/base/stable/10@266200 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f