nvme: Stop probing a removed device

There is no reason the nvme controller can ever return all 1's from
reading the CSTS register. This patch returns an error if we observe
that status. Without this, we may incorrectly proceed with controller
initialization and unnecessarilly rely on error handling to clean this.
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

drivers/nvme/host/core.c

@@ -1086,6 +1086,8 @@ static int nvme_wait_ready(struct nvme_ctrl *ctrl, u64 cap, bool enabled)
 	int ret;
 
 	while ((ret = ctrl->ops->reg_read32(ctrl, NVME_REG_CSTS, &csts)) == 0) {
+		if (csts == ~0)
+			return -ENODEV;
 		if ((csts & NVME_CSTS_RDY) == bit)
 			break;