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

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

Adds a USB packet filter feature to the stack that it could capture
packets which go through each USB host controllers. Its implementations
are almost based on BPF code and very similar with it except it's
little bit customized for USB packet only. The userland program
usbdump(8) would be committed soon.

Discussed with: hps, thompsa, yongari

usb_controller.c requires opt_ddb.h

Remove usb_sw_transfer.[ch] which are now empty after r190735.

Hook up new USB modules.