target/ppc: Add ibm,processor-radix-AP-encodings for TCG

target/ppc: Add ibm,processor-radix-AP-encodings for TCG

The ibm,processor-radix-AP-encodings device tree property of the cpu node
is used to specify the radix mode supported page sizes of the processor
to the guest os. Contained in the top 3 bits of the msb is the actual
page size (AP) encoding associated with the corresponding radix mode
supported page size. Add this property for a TCG guest, note the TCG code
is capable of translating any format so just add the 4 default page sizes.

The ibm,processor-radix-AP-encodings device tree property is defined as:
One to n cells in ascending order of radix mode supported page sizes
encoded as BE ints (32bit on ppc) in the form:
0bxxxyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
- 0bxxx -> AP encoding
- 0byyyyyyyyyyyyyyyyyyyyyyyyyyyyy -> supported page size encoded as a shift

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>