MFC: r249213 (partial)

- Remove unused headers from the SRCS of some modules.
- Use __FBSDID.
- Use DEVMETHOD_END.
- Use NULL instead of 0 for pointers.
MFC: r251115

- Remove pointless returns.
- Make cm_data a void pointer and cm_flags unsigned as appropriate.
MFC: r251133

- Merge from r249476: Ensure that PCI bus BUS_GET_DMA_TAG() method sees
  the actual PCI device which makes the request for DMA tag, instead of
  some descendant of the PCI device, by creating a pass-through trampoline.
- Sprinkle const on tables.
- Use NULL instead of 0 for pointers.
- Take advantage of nitems().
MFC: r251142

- As a follow-up to r247565 (MFC'ed to stable/9 in r248036), make firmware
  images that do not require patching at runtime actually const.
- Remove pointless softc members by employing the corresponding constants
  directly.
- Remove pointless returns.
- Remove unnecessary inclusion of opt_device_polling.h.
- Replace an outdated and now bogus comment in bce_tick() with the
  appropriate one.
MFC: r251394

CAM_DEV_QFREEZE handling should only be done on request submission but
neither on completion nor by SIM drivers in the first place. This issue
has been revealed by r249466.