Fix some USB controller names according to pciconf output.

MFC after:	1 week
Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
Remove the arbitrary binding of the pagedaemon threads to the domains,
update the comment accordingly and make it more precise.

Requested and reviewed by:	jeff (previous version)
Unbreak rwhod(8):

- It did not work with GENERIC kernel after r250603 because
  options PROCDESC was required for pdfork(2).  It now just uses fork(2)
  instead when this syscall is not available.

- Fix verify().  This function was broken in r250602 because the outermost
  "()" was removed from the condition !(isalnum() || ispunct()).
  It prevented hostnames including "-", for example.
Return 0 in nbi->expire when la_expire == 0.  Conversion from time_uptime to
time_second should not be performed in this case.