Use firmware configuration device for boot device, kernel, initrd and
kernel command line parameters on PPC, Sparc32 and Sparc64.

Update OpenBIOS images to r479 which supports the change.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6777 c046a42c-6fe2-441c-8c8c-71466251a162