spapr_events: re-use EPOW event infrastructure for hotplug events

Authored-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_events: event-scan RTAS interface

Authored-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
spapr_pci: emit hotplug add/remove events during hotplug

Guest tools will use these events to automate device setup/teardown.

Note: this interface is undocumented, and potentially racey with
'physical' removal. We can remove the race by tying actual removal
to set-indicator RTAS calls, but should finalize it and document
meant it in SPAPR at some point. For now we restrict this to being
a drmgr-specific extention.

Authored-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
pseries: update SLOF

Image generated from:

https://github.com/mdroth/SLOF/commits/spapr-pci-hotplug-r1

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>