x86, amd: Include linux/elf.h since we use stuff from asm/elf.h

After merging the moduleh tree, today's linux-next build (x86_64
allmodconfig) failed like this:

  arch/x86/kernel/sys_x86_64.c:28:10: warning: 'enum align_flags' declared inside parameter list
  arch/x86/kernel/sys_x86_64.c:28:10: warning: its scope is only this definition or declaration, which is probably not what you
  want arch/x86/kernel/sys_x86_64.c:28:22: error: parameter 3 ('flags') has incomplete type
  [...]

Presumably caused by the module.h split interacting with a
new commit dfb09f9b ("x86, amd: Avoid cache aliasing penalties
on AMD family 15h") from the x8 tree.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Borislav Petkov <borislav.petkov@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Link: http://lkml.kernel.org/r/20110928174214.17a58be15d84d67c185930e1@canb.auug.org.auSigned-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/sys_x86_64.c

@@ -14,6 +14,7 @@
 #include <linux/personality.h>
 #include <linux/random.h>
 #include <linux/uaccess.h>
+#include <linux/elf.h>
 
 #include <asm/ia32.h>
 #include <asm/syscalls.h>