header files: Fix guard name comments to match guard names

This just updates existing guard name comments on the header files
to match the actual #define name.
As a side effect, if there was no newline at the end of these files,
one was added.

Change-Id: Ia2cd8057f2b1ceb0fa1b946e85e0c16a327a04d7
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12900
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/include/cpu/x86/bist.h

@@ -9,4 +9,4 @@ static void report_bist_failure(u32 bist)
 	}
 }
 
-#endif /* CPU_Xf86_BIST_H */
+#endif /* CPU_X86_BIST_H */