alpha: fix formating of stack content

Since version 4.9, the kernel automatically breaks printk calls into
multiple newlines unless pr_cont is used. Fix the alpha stacktrace code,
so that it prints stack trace in four columns, as it was initially
intended.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org	# v4.9+
Signed-off-by: Matt Turner <mattst88@gmail.com>

arch/alpha/kernel/traps.c

@@ -160,11 +160,16 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 	for(i=0; i < kstack_depth_to_print; i++) {
 		if (((long) stack & (THREAD_SIZE-1)) == 0)
 			break;
-		if (i && ((i % 4) == 0))
-			printk("\n       ");
-		printk("%016lx ", *stack++);
+		if ((i % 4) == 0) {
+			if (i)
+				pr_cont("\n");
+			printk("       ");
+		} else {
+			pr_cont(" ");
+		}
+		pr_cont("%016lx", *stack++);
 	}
-	printk("\n");
+	pr_cont("\n");
 	dik_show_trace(sp);
 }