MFC r261423, r261424, r261516, r261513, r261562, r261563, r261564, r261565,
    r261596, r261606

  Add the imx sdhci controller.

  Move Open Firmware device root on PowerPC, ARM, and MIPS systems to
  a sub-node of nexus (ofwbus) rather than direct attach under nexus. This
  fixes FDT on x86 and will make coexistence with ACPI on ARM systems easier.
  SPARC is unchanged.

  Add the missing ')' at end of sentence.  Reword it to use a more common idiom.

  Pass the kernel physical address to initarm through the boot param struct.

  Make functions only used in vfp.c static, and remove vfp_enable.

  Fix __syscall on armeb EABI. As it returns a 64-bit value it needs to
  place 32-bit data in r1, not r0. 64-bit data is already packed correctly.

  Use abp_physaddr for the physical address over KERNPHYSADDR. This helps us
  remove the need to load the kernel at a fixed address.

  Remove references to PHYSADDR where it's used only in debugging output.

  Dynamically generate the page table. This will allow us to detect the
  physical address we are loaded at to change the mapping.