MFC r261982, r261987, r262123, r262244, r262278, r262280, r262353, r262354,
    r262355, r262419,

  Add Vybrid driver for Synchronous Audio Interface (SAI).

  Decrease SAI buffer size. Handle eDMA interrupt on running channel only.

  Give the physmem fdt helper routines static linkage since no global
  definition of them is provided anywhere.

  Add imx6 early printf support, wrapped in #if 0 because it's rarely needed.

  Add basic cpu frequency control and temperature monitoring to imx6_anatop.

  Add the FREEBSD_BOOT_LOADER option so that a loaded DTB passed in from
  ubldr will actually get used.

  Create a generic IMX6 kernel config, then fix it to have an ident line.

  Don't force imx6 bootverbose on anymore, it can be set from ubldr now.
MFC r262394:  Fix parsing multiple roots with whitespace between them.