alpha: notify_cpu_starting() compile fixlet

arch/alpha/kernel/smp.c:153: error: implicit declaration of function 'notify_cpu_starting'
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
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>

arch/alpha/kernel/smp.c

@@ -27,6 +27,7 @@
 #include <linux/cache.h>
 #include <linux/profile.h>
 #include <linux/bitops.h>
+#include <linux/cpu.h>
 
 #include <asm/hwrpb.h>
 #include <asm/ptrace.h>