[S390] fix dump_stack vs. %p and (null)

The s390 implemenation of dump_stack uses %p to display stack content.
Since d97106ab53f812910a62d18afb9dbe882819c1ba (Make %p print '(null)'
for NULL pointers) this causes a strange output for dump_stack:

[...]
Process basename (pid: 8822, task: 00000000b2ece038, ksp: 00000000b24d7b38)
04000000b5685c00 00000000b24d7760 0000000000000002 (null)
00000000b24d7800 00000000b24d7778 00000000b24d7778 00000000001052fe
(null) 00000000b24d7b38 (null) 000000000000000a
000000000000000d (null) 00000000b24d7760 00000000b24d77d8
000000000051a7e8 00000000001052fe 00000000b24d7760 00000000b24d77b0
Call Trace:
[...]

This patch changes our dump_stack to use the appropriate %x format.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/traps.c

@@ -61,9 +61,11 @@ extern pgm_check_handler_t do_asce_exception;
 #define stack_pointer ({ void **sp; asm("la %0,0(15)" : "=&d" (sp)); sp; })
 
 #ifndef CONFIG_64BIT
+#define LONG "%08lx "
 #define FOURLONG "%08lx %08lx %08lx %08lx\n"
 static int kstack_depth_to_print = 12;
 #else /* CONFIG_64BIT */
+#define LONG "%016lx "
 #define FOURLONG "%016lx %016lx %016lx %016lx\n"
 static int kstack_depth_to_print = 20;
 #endif /* CONFIG_64BIT */
@@ -155,7 +157,7 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 			break;
 		if (i && ((i * sizeof (long) % 32) == 0))
 			printk("\n       ");
-		printk("%p ", (void *)*stack++);
+		printk(LONG, *stack++);
 	}
 	printk("\n");
 	show_trace(task, sp);