PPC: Bump qemu-system-ppc to 64-bit physical address space

Some 32-bit PPC CPUs can use up to 36 bit of physical address space.
Treat them accordingly in the qemu-system-ppc binary type.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/configure b/configure
index 4f87e0a..f8dd4db 100755
--- a/configure
+++ b/configure
@@ -3309,7 +3309,7 @@
   ;;
   ppc)
     gdb_xml_files="power-core.xml power-fpu.xml power-altivec.xml power-spe.xml"
-    target_phys_bits=32
+    target_phys_bits=64
     target_nptl="yes"
     target_libs_softmmu="$fdt_libs"
   ;;