SMP: Add arch-agnostic boot_cpu()

We should not have x86 specific includes in lib/.

Change-Id: I18fa9c8017d65c166ffd465038d71f35b30d6f3d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5156
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/include/cpu/x86/lapic.h

@@ -4,6 +4,7 @@
 #include <cpu/x86/lapic_def.h>
 #include <cpu/x86/msr.h>
 #include <arch/hlt.h>
+#include <smp/node.h>
 
 /* See if I need to initialize the local apic */
 #if CONFIG_SMP || CONFIG_IOAPIC
@@ -153,10 +154,4 @@ int start_cpu(struct device *cpu);
 
 #endif /* !__PRE_RAM__ */
 
-#if CONFIG_SMP
-int boot_cpu(void);
-#else
-#define boot_cpu(x) 1
-#endif
-
 #endif /* CPU_X86_LAPIC_H */