Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- With the demise of !ATA_CAM, ATA_STATIC_ID is the only ata(4) related
option left but actually consumed by ada(4), so move it to opt_ada.h
and get rid of opt_ata.h.
- Fix stand-alone build of atacore(4) by adding opt_cam.h.
- Use __FBSDID.
- Use DEVMETHOD_END.
- Use NULL instead of 0 for pointers.

Hook up new USB modules.