Don't denounce peripherals on system shutdown. Together with r267321,
we're now back to the pre-r228483 level of default verbosity. This in
turn again typically allows for reading information that userland might
have printed on the screen before initiating a halt, but still permits
to debug potential device shutdown problems on system shutdown via
CAM_DEBUG etc.

Reviewed by:	mav
MFC after:	3 days
Sponsored by:	Bally Wulff Games & Entertainment GmbH