x86: Fix ASM_X86__ header guards

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/srat.h b/arch/x86/include/asm/srat.h
index 5363e4f..b508d63 100644
--- a/arch/x86/include/asm/srat.h
+++ b/arch/x86/include/asm/srat.h
@@ -24,8 +24,8 @@
  * Send feedback to Pat Gaughen <gone@us.ibm.com>
  */
 
-#ifndef ASM_X86__SRAT_H
-#define ASM_X86__SRAT_H
+#ifndef _ASM_X86_SRAT_H
+#define _ASM_X86_SRAT_H
 
 #ifdef CONFIG_ACPI_NUMA
 extern int get_memcfg_from_srat(void);
@@ -36,4 +36,4 @@
 }
 #endif
 
-#endif /* ASM_X86__SRAT_H */
+#endif /* _ASM_X86_SRAT_H */