x86: consolidate header guards

This patch is the result of an automatic script that consolidates the
format of all the headers in include/asm-x86/.

The format:

1. No leading underscore. Names with leading underscores are reserved.
2. Pathname components are separated by two underscores. So we can
   distinguish between mm_types.h and mm/types.h.
3. Everything except letters and numbers are turned into single
   underscores.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
diff --git a/include/asm-x86/io_apic.h b/include/asm-x86/io_apic.h
index 14f82bb..be62847 100644
--- a/include/asm-x86/io_apic.h
+++ b/include/asm-x86/io_apic.h
@@ -1,5 +1,5 @@
-#ifndef __ASM_IO_APIC_H
-#define __ASM_IO_APIC_H
+#ifndef ASM_X86__IO_APIC_H
+#define ASM_X86__IO_APIC_H
 
 #include <linux/types.h>
 #include <asm/mpspec.h>
@@ -189,4 +189,4 @@
 static inline void ioapic_init_mappings(void) { }
 #endif
 
-#endif
+#endif /* ASM_X86__IO_APIC_H */