x86: remove pointless comments

Remove old comments that include the old arch/i386 directory.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/boot/boot.h

@@ -9,8 +9,6 @@
  * ----------------------------------------------------------------------- */
 
 /*
- * arch/i386/boot/boot.h
- *
  * Header file for the real-mode kernel code
  */