powerpc/mpic_msgr: fix compile error when SMP disabled

In file included from arch/powerpc/sysdev/mpic_msgr.c:20:0:
~/arch/powerpc/include/asm/mpic_msgr.h: In function 'mpic_msgr_set_destination':
~/arch/powerpc/include/asm/mpic_msgr.h:117:2:
error: implicit declaration of function 'get_hard_smp_processor_id'
make[1]: *** [arch/powerpc/sysdev/mpic_msgr.o] Error 1

Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/include/asm/mpic_msgr.h

@@ -13,6 +13,7 @@
 
 #include <linux/types.h>
 #include <linux/spinlock.h>
+#include <asm/smp.h>
 
 struct mpic_msgr {
 	u32 __iomem *base;