powerpc: Various UP build fixes

Mostly this involves adding #include <asm/smp.h>, since that defines
things like boot_cpuid[_phys] and [gs]et_hard_smp_processor_id, which
are SMP-related but still needed on UP.  This incorporates fixes
posted by Olof Johansson and Heikki Lindholm.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc64/kernel/idle.c b/arch/ppc64/kernel/idle.c
index 8abd2ad..8fec274 100644
--- a/arch/ppc64/kernel/idle.c
+++ b/arch/ppc64/kernel/idle.c
@@ -28,6 +28,7 @@
 #include <asm/time.h>
 #include <asm/systemcfg.h>
 #include <asm/machdep.h>
+#include <asm/smp.h>
 
 extern void power4_idle(void);