powerpc/pseries: Query hypervisor for count cache flush settings

powerpc/pseries: Query hypervisor for count cache flush settings

Use the existing hypercall to determine the appropriate settings for
the count cache flush, and then call the generic powerpc code to set
it up based on the security feature flags.

BugLink: https://bugs.launchpad.net/bugs/1822870
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit ba72dc171954b782a79d25e0f4b3ed91090c3b1e)
Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>