Fix acpi_video loading.  When we started cleaning up the duplicate handles left around after the PCI probe, acpi_video stopped attaching because while it was an acpi child device, it really is a PCI device.  Fix this by making it a PCI child.
Fix acpi_video loading.  When we started cleaning up the duplicate handles
left around after the PCI probe, acpi_video stopped attaching because while
it was an acpi child device, it really is a PCI device.  Fix this by making
it a PCI child.

* Remove non-handle ivars accesses since child busses only implement
acpi_get_handle().
* Access the acpi softc directly through the devclass instead of through
the implied parent.
* Clean up a potential panic on unload by freeing the sysctl context before
storing NULL in the OID.

Found by:	marks

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase