PPC: E500: Set PIR default reset value rather than SPR value

We now reset SPRs to their reset values on CPU reset. So if we want
to have an SPR persistently changed, we need to change its default
reset value rather than the value itself manually.

Do this for SPR_BOOKE_PIR, fixing e500v2 SMP boot.

Reported-by: Frederic Konrad <fred.konrad@greensocs.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Tested-by: KONRAD Frederic <fred.konrad@greensocs.com>
pseries: Update SLOF firmware image to qemu-slof-20140404

The change log is:
  > Isolate sc 1 detection logic
  > build: auto-detect ppc64 architecture
  > cas: increase hcall buffer size to accomodate 256 cpus
  > usb: change device tree naming
  > usb-core: adjust port numbers in set_address
  > virtio-scsi: correct srplun comment
  > Fix kernel loading
  > Workaround to make grub2 assign server ip from dhcp ack packet only
  > ELF: Enter LE binary in LE mode
  > ELF loading should fail for virt != phys

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>