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 <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Cc: Ivan Kokshaysky <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/alpha/kernel/smp.c

···
 #include <linux/cache.h>
 #include <linux/profile.h>
 #include <linux/bitops.h>
+#include <linux/cpu.h>
 
 #include <asm/hwrpb.h>
 #include <asm/ptrace.h>