x86, apic: Include module.h header in apic_flat_64.c

apic_flat_64.c needs to include module.h because it uses
EXPORT_SYMBOL_GPL().

This fixes these warnings on some !SMP randconfigs:

  arch/x86/kernel/apic/apic_flat_64.c:31: warning: data definition has no type or storage class
  arch/x86/kernel/apic/apic_flat_64.c:31: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL'
  arch/x86/kernel/apic/apic_flat_64.c:31: warning: parameter names (without types) in function declaration
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20110523104300.dd532a99.randy.dunlap@oracle.comSigned-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/apic/apic_flat_64.c

@@ -16,6 +16,7 @@
 #include <linux/ctype.h>
 #include <linux/init.h>
 #include <linux/hardirq.h>
+#include <linux/module.h>
 #include <asm/smp.h>
 #include <asm/apic.h>
 #include <asm/ipi.h>