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

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


CVE: NA

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If CONFIG_SCSI_VIRTIO is set as "y", sdev->host->hostt->module will be
NULL, which means scsi device can't be probed normally.

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

Fixes: 3f4659e76aa3 ("[Huawei] scsi: scsi_device_gets returns failure when the module is NULL.")
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>