MFC 256941: make sure the frame is indeed in the kernel memory.
MFC 256873: Make watchdog function conform watchdog(9):
MFC 256942, 256943:

  - Fix a typo.
  - Use bus_dmamap_unload(), it is not optional.
  - The new allocator won't return coherent memory for any size > PAGE_SIZE,
  so don't assume we have coherent memory, and explicitely use
  bus_dmamap_sync().
MFC 257189:

  Fix an itt instruction. We need to execute both the mov and b instructions
  when building for Thumb.