ppc patch queue 2020-02093 This pull request supersedes ppc-for-5.0-20200131. The only changes are one extra patch to suppress some irritating warnings during tests under TCG, and an extra Tested-by in one of the other patches. Here's the next batch of patches for ppc and associated machine types. Highlights includes: * Remove the deprecated "prep" machine type and its OpenHackware firmware * Add TCG emulation of the msgsndp etc. supervisor privileged doorbell instructions * Allow "pnv" machine type to run Hostboot style firmwares * Add a virtual TPM device for spapr machines * Implement devices for POWER8 PHB3 and POWER9 PHB4 host bridges for the pnv machine type * Use faster Spectre mitigation by default for POWER9 DD2.3 machines * Introduce Firmware Assisted NMI dump facility for spapr machines * Fix a performance regression with load/store multiple instructions in TCG as well as some other assorted cleanups and fixes.