K 10
svn:author
V 3
avg
K 8
svn:date
V 27
2018-05-05T05:19:32.870493Z
K 7
svn:log
V 910
for bus suspend, detach and shutdown iterate children in reverse order

For most buses all children are equal, so the order does not matter.
Other buses, such as acpi, carefully order their child devices to
express implicit dependencies between them.  For such buses it is safer
to bring down devices in the reverse order.

I believe that this is the reason why hpet_suspend had to be disabled.
Some drivers depend on a working event timer until they are suspended.
But previously we would suspend hpet very early.

I tested this change by makinbg hpet_suspend actually stop HPET timers
and tested that too.

Note that this change is not a complete solution as it does not take
into account bus passes.
A better approach would be to track the actual attach order of the
devices and to use the reverse of that.

Reviewed by:	imp, mav
MFC after:	3 weeks
Differential Revision: https://reviews.freebsd.org/D15291

END