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/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index bc5553b..3ee338c 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -16,7 +16,7 @@
  */
 #undef CONFIG_PARAVIRT
 #ifdef CONFIG_X86_32
-#define _ASM_DESC_H_ 1
+#define ASM_X86__DESC_H 1
 #endif
 
 #ifdef CONFIG_X86_64