m68k: remove unused asm/dbg.h

The contents of the m68k asm/dbg.h are never used, remove the file and
remove the one reference to it.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/include/asm/dbg.h

-#define DEBUG 1
-#ifdef CONFIG_COLDFIRE
-#define	BREAK asm volatile ("halt")
-#else
-#define BREAK *(volatile unsigned char *)0xdeadbee0 = 0
-#endif

drivers/tty/serial/68328serial.c

@@ -14,7 +14,6 @@
  * 2.4/2.5 port                 David McCullough
  */
 
-#include <asm/dbg.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/serial.h>