powerpc/pmac: Don't register pmac PIC syscore ops when HW not present

The Apple custom PIC only exist in some earlier machine models, anything with an MPIC will crash on suspend if we register those syscore ops unconditionally.

This is a regression caused by:

f5a592f7d74e38c5007876c731e6bf5580072e63
PM / PowerPC: Use struct syscore_ops instead of sysdevs for PM

---

Linus, can you just pop that in ? I can put it in a git tree tomorrow if you prefer...

 arch/powerpc/platforms/powermac/pic.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

index 9089b04..7667db4 100644
@@ -715,7 +715,8 @@ static struct syscore_ops pmacpic_syscore_ops = {
 
 static int __init init_pmacpic_syscore(void)
 {
-	register_syscore_ops(&pmacpic_syscore_ops);
+	if (pmac_irq_hw[0])
+		register_syscore_ops(&pmacpic_syscore_ops);
 	return 0;
 }