powerpc/pseries: Add H_GET_CPU_CHARACTERISTICS flags & wrapper

commit 191eccb1580939fb0d47deb405b82a85b0379070 upstream.

A new hypervisor call has been defined to communicate various
characteristics of the CPU to guests. Add definitions for the hcall
number, flags and a wrapper function.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[Balbir fixed conflicts in backport]
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>