Merge remote-tracking branch 'remotes/gkurz/tags/ppc-for-5.2-20201118' into staging

ppc patch queue for 2020-11-18

This fixes a regression that badly breaks some guest setups because
IPIs end up misconfigured in the XIVE interrupt controller. Hopefully,
the last fix for sPAPR. I'm sending this PR with the blessing of David
who is currently on holidays.

# gpg: Signature made Wed 18 Nov 2020 10:26:31 GMT
# gpg:                using RSA key B4828BAF943140CEF2A3491071D4D5E5822F73D6
# gpg: Good signature from "Greg Kurz <groug@kaod.org>" [full]
# gpg:                 aka "Gregory Kurz <gregory.kurz@free.fr>" [full]
# gpg:                 aka "[jpeg image of size 3330]" [full]
# Primary key fingerprint: B482 8BAF 9431 40CE F2A3  4910 71D4 D5E5 822F 73D6

* remotes/gkurz/tags/ppc-for-5.2-20201118:
  Revert series "spapr/xive: Allocate vCPU IPIs from the vCPU contexts"

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>