MFC r219048, r219004, r218475 and r204632.

• The NetBSD Foundation has granted permission to remove clause 3 and 4 from their software.
• use device_printf() instead of printf() to give more accurate warnings.
• use memcpy() instead of bcopy().
• add missing #if's for non-FreeBSD compilation.
• Add missing xhci(4) manual page.
• Minor update in some USB manual pages.
• Correct USB 3.0 wire-speed to 5.0Gbps

Approved by: thompsa (mentor)