alpha: fix hard_smp_processor_id compile error

"Remove hardcoding of hard_smp_processor_id on UP systems",
2f4dfe20 in Linus' tree, moved
the definition of hard_smp_processor_id linux/smp.h to asm/smp.h
for UP systems. This causes a regression on Alpha.

cc1: warnings being treated as errors
arch/alpha/kernel/setup.c: In function 'setup_arch':
arch/alpha/kernel/setup.c:506: warning: implicit declaration of function 'hard_smp_processor_id'
make[1]: *** [arch/alpha/kernel/setup.o] error 1
make: *** [arch/alpha/kernel] error 2

By including asm/smp.h non-conditionally in asm/mmu_context.h
the problem appears to be resolved.

Cc: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Simon Horman <horms@verge.net.au>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-alpha/mmu_context.h

@@ -85,8 +85,8 @@ __reload_thread(struct pcb_struct *pcb)
  * +-------------+----------------+--------------+
  */
 
-#ifdef CONFIG_SMP
 #include <asm/smp.h>
+#ifdef CONFIG_SMP
 #define cpu_last_asn(cpuid)	(cpu_data[cpuid].last_asn)
 #else
 extern unsigned long last_asn;