powerpc/kexec: Switch to a static PACA on the way out

With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
static data and there is a chance that something may stomp it when preparing
to kexec.  This patch switches this final CPU to a static PACA just before
we pull the switch.

Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 8ce7963..1ff6662 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -146,7 +146,7 @@
 extern struct paca_struct *paca;
 extern __initdata struct paca_struct boot_paca;
 extern void initialise_paca(struct paca_struct *new_paca, int cpu);
-
+extern void setup_paca(struct paca_struct *new_paca);
 extern void allocate_pacas(void);
 extern void free_unused_pacas(void);