ppc/spapr: Add "ibm,pa-features" property to the device-tree

ppc/spapr: Add "ibm,pa-features" property to the device-tree

LoPAPR defines a "ibm,pa-features" per-CPU device tree property which
describes extended features of the Processor Architecture.

This adds the property to the device tree. At the moment this is the
copy of what pHyp advertises except "I=1 (cache inhibited) Large Pages"
which is enabled for TCG and disabled when running under HV KVM host
with 4K system page size.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[aik: rebased, changed commit log, moved ci_large_pages initialization,
renamed pa_features arrays]
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>