If scsi_host_lookup() fails we will jump to put_host which may cause a
panic. Jump to exit_set_fnode instead.

Link: https://lore.kernel.org/r/20200615081226.183068-1-jingxiangfeng@huawei.comReviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>