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

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.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>