drm: radeon: fix printk format warning

drivers/gpu/drm/radeon/radeon_atpx_handler.c:151:3: warning: format '%lu' expects type 'long unsigned int', but argument 2 has type 'size_t'

[airlied: Alex had others fixed already, except for atpx one]
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atpx_handler.c

@@ -148,7 +148,7 @@ static int radeon_atpx_verify_interface(struct radeon_atpx *atpx)
 
 	size = *(u16 *) info->buffer.pointer;
 	if (size < 8) {
-		printk("ATPX buffer is too small: %lu\n", size);
+		printk("ATPX buffer is too small: %zu\n", size);
 		err = -EINVAL;
 		goto out;
 	}