MFC r261351, r261352, r261355, r261396, r261397, r261398, r261403, r261404,

MFC r261351, r261352, r261355, r261396, r261397, r261398, r261403, r261404,
    r261405

  Open Firmware interrupt specifiers can consist of arbitrary-length byte
  strings and include arbitrary information (IRQ line/domain/sense). When the
  ofw_bus_map_intr() API was introduced, it assumed that, as on most systems,
  these were either 1 cell, containing an interrupt line, or 2, containing
  a line number plus a sense code. It turns out a non-negligible number of
  ARM systems use 3 (or even 4!) cells for interrupts, so make this more
  general.

  Provide a simpler and more standards-compliant simplebus implementation to
  get the Routerboard 800 up and running with the vendor device tree. This
  does not implement some BERI-specific features (which hopefully won't be
  necessary soon), so move the old code to mips/beri, with a higher attach
  priority when built, until MIPS interrupt domain support is rearranged.

  Allow nesting of simplebuses.

  Add a set of helpers (ofw_bus_get_status() and ofw_bus_status_okay()) to
  process "status" properties of OF nodes.

  Fix one remnant endian flaw in nexus.

git-svn-id: svn://svn.freebsd.org/base/stable/10@266128 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f