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>

arch/powerpc/platforms/pseries/iommu.c

@@ -46,6 +46,7 @@
 #include <asm/firmware.h>
 #include <asm/tce.h>
 #include <asm/ppc-pci.h>
+#include <asm/udbg.h>
 
 #include "plpar_wrappers.h"