um: Remove dead code from stacktrace

Remove left over code from commit 970e51fe
(um: Add support for CONFIG_STACKTRACE)
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/sysrq.c

@@ -29,7 +29,7 @@ static const struct stacktrace_ops stackops = {
 
 void show_stack(struct task_struct *task, unsigned long *stack)
 {
-	unsigned long *sp = stack, bp = 0;
+	unsigned long *sp = stack;
 	struct pt_regs *segv_regs = current->thread.segv_regs;
 	int i;
 
@@ -39,10 +39,6 @@ void show_stack(struct task_struct *task, unsigned long *stack)
 		return;
 	}
 
-#ifdef CONFIG_FRAME_POINTER
-	bp = get_frame_pointer(task, segv_regs);
-#endif
-
 	if (!stack)
 		sp = get_stack_pointer(task, segv_regs);