block: constify the whole_disk device_attribute

The struct is never modified so it can be const.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230419-const-partition-v3-4-4e14e48be367@weissschuh.netSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/partitions/core.c

@@ -288,7 +288,7 @@ static ssize_t whole_disk_show(struct device *dev,
 {
 	return 0;
 }
-static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
+static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 
 /*
  * Must be called either with open_mutex held, before a disk can be opened or