x86, cpu: Clean up AMD erratum 400 workaround

Remove check_c1e_idle() and use the new AMD errata checking framework
instead.

Signed-off-by: Hans Rosenfeld <hans.rosenfeld@amd.com>
LKML-Reference: <1280336972-865982-2-git-send-email-hans.rosenfeld@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5084c2f..eebdc1f 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -1029,6 +1029,7 @@
  * AMD errata checking
  */
 #ifdef CONFIG_CPU_SUP_AMD
+extern const int amd_erratum_400[];
 extern bool cpu_has_amd_erratum(const int *);
 
 #define AMD_LEGACY_ERRATUM(...)		{ -1, __VA_ARGS__, 0 }