powerpc: Move smp_mpic_message_pass into mpic.c

Having it here rather than in arch/ppc64/kernel/smp.c means that
we can use it on 32-bit SMP systems easily with ARCH=powerpc.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/mpic.h b/include/asm-powerpc/mpic.h
index 6b558ae..7083d1f 100644
--- a/include/asm-powerpc/mpic.h
+++ b/include/asm-powerpc/mpic.h
@@ -273,6 +273,9 @@
 /* Send an IPI (non offseted number 0..3) */
 extern void mpic_send_ipi(unsigned int ipi_no, unsigned int cpu_mask);
 
+/* Send a message (IPI) to a given target (cpu number or MSG_*) */
+void smp_mpic_message_pass(int target, int msg);
+
 /* Fetch interrupt from a given mpic */
 extern int mpic_get_one_irq(struct mpic *mpic, struct pt_regs *regs);
 /* This one gets to the primary mpic */