includecheck fix: x86, shadow.c

fix the following 'make includecheck' warning:

  arch/x86/mm/kmemcheck/shadow.c: linux/module.h is included more than once.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <1247065179.4382.51.camel@ht.satnam>