x86: ds.c ptrace.c integer as NULL pointer sparse fixes

fix:

 arch/x86/kernel/ptrace.c:763:29: warning: Using plain integer as NULL pointer
 arch/x86/kernel/ptrace.c:777:46: warning: Using plain integer as NULL pointer
 arch/x86/kernel/ptrace.c:1115:45: warning: Using plain integer as NULL pointer
 arch/x86/kernel/ds.c:482:26: warning: Using plain integer as NULL pointer
 arch/x86/kernel/ds.c:487:25: warning: Using plain integer as NULL pointer
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ds.c

@@ -479,12 +479,12 @@ static int ds_release(struct task_struct *task, enum ds_qualifier qual)
 		goto out;
 
 	kfree(context->buffer[qual]);
-	context->buffer[qual] = 0;
+	context->buffer[qual] = NULL;
 
 	current->mm->total_vm  -= context->pages[qual];
 	current->mm->locked_vm -= context->pages[qual];
 	context->pages[qual] = 0;
-	context->owner[qual] = 0;
+	context->owner[qual] = NULL;
 
 	/*
 	 * we put the context twice:

arch/x86/kernel/ptrace.c

@@ -734,7 +734,7 @@ static int ptrace_bts_config(struct task_struct *child,
 		goto errout;
 
 	if (cfg.flags & PTRACE_BTS_O_ALLOC) {
-		ds_ovfl_callback_t ovfl = 0;
+		ds_ovfl_callback_t ovfl = NULL;
 		unsigned int sig = 0;
 
 		/* we ignore the error in case we were not tracing child */
@@ -748,7 +748,7 @@ static int ptrace_bts_config(struct task_struct *child,
 			ovfl = ptrace_bts_ovfl;
 		}
 
-		error = ds_request_bts(child, /* base = */ 0, cfg.size, ovfl);
+		error = ds_request_bts(child, /* base = */ NULL, cfg.size, ovfl);
 		if (error < 0)
 			goto errout;
 
@@ -1086,7 +1086,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 		break;
 
 	case PTRACE_BTS_SIZE:
-		ret = ds_get_bts_index(child, /* pos = */ 0);
+		ret = ds_get_bts_index(child, /* pos = */ NULL);
 		break;
 
 	case PTRACE_BTS_GET: