target/ppc: Pass cpu instead of env to ppc_create_page_sizes_prop()

As a rule we prefer to pass PowerPCCPU instead of CPUPPCState, and this
change will make some things simpler later on.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

include/hw/ppc/fdt.h

@@ -23,7 +23,7 @@
         }                                                          \
     } while (0)
 
-size_t ppc_create_page_sizes_prop(CPUPPCState *env, uint32_t *prop,
+size_t ppc_create_page_sizes_prop(PowerPCCPU *cpu, uint32_t *prop,
                                   size_t maxsize);
 
 #endif /* PPC_FDT_H */