nvme/pci: Fix write and poll queue types

The number of poll or write queues should never be negative. Use unsigned
types so that it's not possible to break have the driver not allocate
any queues.
Reviewed-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NKeith Busch <kbusch@kernel.org>

drivers/nvme/host/pci.c

@@ -68,14 +68,14 @@ static int io_queue_depth = 1024;
 module_param_cb(io_queue_depth, &io_queue_depth_ops, &io_queue_depth, 0644);
 MODULE_PARM_DESC(io_queue_depth, "set io queue depth, should >= 2");
 
-static int write_queues;
-module_param(write_queues, int, 0644);
+static unsigned int write_queues;
+module_param(write_queues, uint, 0644);
 MODULE_PARM_DESC(write_queues,
 	"Number of queues to use for writes. If not set, reads and writes "
 	"will share a queue set.");
 
-static int poll_queues;
-module_param(poll_queues, int, 0644);
+static unsigned int poll_queues;
+module_param(poll_queues, uint, 0644);
 MODULE_PARM_DESC(poll_queues, "Number of queues to use for polled IO.");
 
 struct nvme_dev;