nvme: use UINT_MAX for max discard sectors

It's more elegant to use UINT_MAX to represent the max value of
type unsigned int. So replace the actual value by using this define.
Signed-off-by: Minfei Huang <mnghuan@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/nvme/host/core.c

@@ -781,7 +781,7 @@ static void nvme_config_discard(struct nvme_ns *ns)
 
 	ns->queue->limits.discard_alignment = logical_block_size;
 	ns->queue->limits.discard_granularity = logical_block_size;
-	blk_queue_max_discard_sectors(ns->queue, 0xffffffff);
+	blk_queue_max_discard_sectors(ns->queue, UINT_MAX);
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue);
 }