x86, setup: Rename BOOT_ISDIGIT_H to BOOT_CTYPE_H

arch/x86/boot/isdigit.h was renamed to arch/x86/boot/ctype.h in
6238b47b ("x86, setup: move isdigit.h to ctype.h, header files on top.")
Adjust guards too.
Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Link: http://lkml.kernel.org/r/1420267941-26390-1-git-send-email-kuleshovmail@gmail.comSigned-off-by: NBorislav Petkov <bp@suse.de>

arch/x86/boot/ctype.h

-#ifndef BOOT_ISDIGIT_H
-
-#define BOOT_ISDIGIT_H
+#ifndef BOOT_CTYPE_H
+#define BOOT_CTYPE_H
 
 static inline int isdigit(int ch)
 {