powerpc/smp: smp_ops->kick_cpu() should be able to fail

When we start a cpu we use smp_ops->kick_cpu(), which currently
returns void, it should be able to fail. Convert it to return
int, and update all uses.

Convert all the current error cases to return -ENOENT, which is
what would eventually be returned by __cpu_up() currently when
it doesn't detect the cpu as coming up in time.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index bb4c033..5087349 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -150,7 +150,7 @@
 
 extern int smp_mpic_probe(void);
 extern void smp_mpic_setup_cpu(int cpu);
-extern void smp_generic_kick_cpu(int nr);
+extern int smp_generic_kick_cpu(int nr);
 
 extern void smp_generic_give_timebase(void);
 extern void smp_generic_take_timebase(void);