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>

arch/powerpc/platforms/chrp/smp.c

@@ -30,10 +30,12 @@
 #include <asm/mpic.h>
 #include <asm/rtas.h>
 
-static void __devinit smp_chrp_kick_cpu(int nr)
+static int __devinit smp_chrp_kick_cpu(int nr)
 {
 	*(unsigned long *)KERNELBASE = nr;
 	asm volatile("dcbf 0,%0"::"r"(KERNELBASE):"memory");
+
+	return 0;
 }
 
 static void __devinit smp_chrp_setup_cpu(int cpu_nr)