[S390] Add oops_enter()/oops_exit() calls to die().

This is mainly to switch off all potentially debugging stuff that
won't report anything useful after an oops happened.
Besided that setting pause_on_oops will work too, but doesn't make
too much sense on s390.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/traps.c

@@ -253,20 +253,22 @@ void die(const char * str, struct pt_regs * regs, long err)
 {
 	static int die_counter;
 
+	oops_enter();
 	debug_stop_all();
 	console_verbose();
 	spin_lock_irq(&die_lock);
 	bust_spinlocks(1);
 	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 	print_modules();
-        show_regs(regs);
+	show_regs(regs);
 	bust_spinlocks(0);
-        spin_unlock_irq(&die_lock);
+	spin_unlock_irq(&die_lock);
 	if (in_interrupt())
 		panic("Fatal exception in interrupt");
 	if (panic_on_oops)
 		panic("Fatal exception: panic_on_oops");
-        do_exit(SIGSEGV);
+	oops_exit();
+	do_exit(SIGSEGV);
 }
 
 static void inline