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/ldt.h b/arch/x86/include/asm/ldt.h
index a522850..46727eb 100644
--- a/arch/x86/include/asm/ldt.h
+++ b/arch/x86/include/asm/ldt.h
@@ -3,8 +3,8 @@
  *
  * Definitions of structures used with the modify_ldt system call.
  */
-#ifndef ASM_X86__LDT_H
-#define ASM_X86__LDT_H
+#ifndef _ASM_X86_LDT_H
+#define _ASM_X86_LDT_H
 
 /* Maximum number of LDT entries supported. */
 #define LDT_ENTRIES	8192
@@ -37,4 +37,4 @@
 #define MODIFY_LDT_CONTENTS_CODE	2
 
 #endif /* !__ASSEMBLY__ */
-#endif /* ASM_X86__LDT_H */
+#endif /* _ASM_X86_LDT_H */