The 'cpu_version' field in PowerPCCPU is badly named.  It's named after the
'cpu-version' device tree property where it is advertised, but that meaning
may not be obvious in most places it appears.

Worse, it doesn't even really correspond to that device tree property.  The
property contains either the processor's PVR, or, if the CPU is running in
a compatibility mode, a special "logical PVR" representing which mode.

Rename the cpu_version field, and a number of related variables to
compat_pvr to make this clearer.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: NThomas Huth <thuth@redhat.com>