s390/debug: use union tod_clock

static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,

				      int level, int exception)

{

	unsigned char clk[STORE_CLOCK_EXT_SIZE];

	unsigned long timestamp;

	union tod_clock clk;

	get_tod_clock_ext(clk);

	timestamp = *(unsigned long *) &clk[0] >> 4;

	store_tod_clock_ext(&clk);

	timestamp = clk.us;

	timestamp -= TOD_UNIX_EPOCH >> 12;

	active->clock = timestamp;

	active->cpu = smp_processor_id();