drm/radeon: NULL noise: drivers/gpu/drm/radeon/radeon_*.c

Fix this sparse warning:
  drivers/gpu/drm/radeon/r600_cp.c:1811:52: warning: Using plain integer as NULL pointer
  drivers/gpu/drm/radeon/radeon_cp.c:1363:52: warning: Using plain integer as NULL pointer
  drivers/gpu/drm/radeon/radeon_state.c:1983:61: warning: Using plain integer as NULL pointer

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r600_cp.c

@@ -1811,7 +1811,7 @@ int r600_do_cleanup_cp(struct drm_device *dev)
 
 		if (dev_priv->gart_info.gart_table_location == DRM_ATI_GART_FB) {
 			drm_core_ioremapfree(&dev_priv->gart_info.mapping, dev);
-			dev_priv->gart_info.addr = 0;
+			dev_priv->gart_info.addr = NULL;
 		}
 	}
 	/* only clear to the start of flags */

drivers/gpu/drm/radeon/radeon_cp.c

@@ -1541,7 +1541,7 @@ static int radeon_do_cleanup_cp(struct drm_device * dev)
 		if (dev_priv->gart_info.gart_table_location == DRM_ATI_GART_FB)
 		{
 			drm_core_ioremapfree(&dev_priv->gart_info.mapping, dev);
-			dev_priv->gart_info.addr = 0;
+			dev_priv->gart_info.addr = NULL;
 		}
 	}
 	/* only clear to the start of flags */

drivers/gpu/drm/radeon/radeon_state.c

@@ -1986,7 +1986,7 @@ static int alloc_surface(drm_radeon_surface_alloc_t *new,
 
 	/* find a virtual surface */
 	for (i = 0; i < 2 * RADEON_MAX_SURFACES; i++)
-		if (dev_priv->virt_surfaces[i].file_priv == 0)
+		if (dev_priv->virt_surfaces[i].file_priv == NULL)
 			break;
 	if (i == 2 * RADEON_MAX_SURFACES) {
 		return -1;