x86: consolidate header guards

This patch consolidates the header guard names which are also used
externally, i.e. in .c files.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
diff --git a/include/asm-x86/desc.h b/include/asm-x86/desc.h
index a44c4dc..b73fea5 100644
--- a/include/asm-x86/desc.h
+++ b/include/asm-x86/desc.h
@@ -1,5 +1,5 @@
-#ifndef _ASM_DESC_H_
-#define _ASM_DESC_H_
+#ifndef ASM_X86__DESC_H
+#define ASM_X86__DESC_H
 
 #ifndef __ASSEMBLY__
 #include <asm/desc_defs.h>
@@ -397,4 +397,4 @@
 
 #endif /* __ASSEMBLY__ */
 
-#endif
+#endif /* ASM_X86__DESC_H */