scsi: don't fail if hostt->module is NULL

hulk inclusion
category: bugfix
bugzilla: 189103, https://gitee.com/openeuler/kernel/issues/I7YWV4


CVE: NA

--------------------------------

If CONFIG_SCSI_VIRTIO is set as "y", sdev->host->hostt->module will be
NULL, which means scsi device can't be probed normally.
This problem was introduced  by
"scsi: scsi_device_gets returns failure when the module is NULL".

Fix the problem by adding a member in struct Scsi_Host to record whether
the module is builtin.

Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
conflict:
  drivers/scsi/hosts.c
Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>