KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm

KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm

This splits out the handling of "fake suspend" mode, part of the
hypervisor TM assist code for POWER9, and puts almost all of it in
new kvmppc_save_tm_hv and kvmppc_restore_tm_hv functions.  The new
functions branch to kvmppc_save/restore_tm if the CPU does not
require hypervisor TM assistance.

With this, it will be more straightforward to move kvmppc_save_tm and
kvmppc_restore_tm to another file and use them for transactional
memory support in PR KVM.  Additionally, it also makes the code a
bit clearer and reduces the number of feature sections.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
(cherry picked from commit 7b0e827c6970e8ca77c60ae87592204c39e41245)
CVE-2020-8834
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Marcelo Cerri <marcelo.cerri@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>