KVM: PPC: Book3S HV P9: Fix irq disabling in tick accounting

kvmhv_run_single_vcpu() disables PMIs as well as Linux irqs,
however the tick time accounting code enables and disables irqs and
not PMIs within this region. By chance this might not actually cause
a bug, but it is clearly an incorrect use of the APIs.

Fixes: 2251fbe7 ("KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220908132545.4085849-2-npiggin@gmail.com