PPC32: Simplify the BUG() implementation for now (a better one is coming).

include/asm-ppc/bug.h

 #ifndef _PPC_BUG_H
 #define _PPC_BUG_H
 
-#include <linux/config.h>
-#include <asm/xmon.h>
-
-#ifdef CONFIG_XMON
-extern void xmon(struct pt_regs *);
-#define BUG() do { \
-	printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
-	xmon(0); \
-} while (0)
-#else
 #define BUG() do { \
 	printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
 	__asm__ __volatile__(".long 0x0"); \
 } while (0)
-#endif
+
 #define PAGE_BUG(page) do { BUG(); } while (0)
 
 #endif