ppc patch queue for 2021-03-10 Next batch of patches for the ppc target and machine types. Includes: * Several cleanups for sm501 from Peter Maydell * An update to the SLOF guest firmware * Improved handling of hotplug failures in spapr, associated cleanups to the hotplug handling code * Several etsec fixes and cleanups from Bin Meng * Assorted other fixes and cleanups