CVE-2021-47480

In the Linux kernel, the following vulnerability has been resolved:

scsi: core: Put LLD module refcnt after SCSI device is released

SCSI host release is triggered when SCSI device is freed. We have to make
sure that the low-level device driver module won't be unloaded before SCSI
host instance is released because shost->hostt is required in the release
handler.

Make sure to put LLD module refcnt after SCSI device is released.

Fixes a kernel panic of 'BUG: unable to handle page fault for address'
reported by Changhui and Yi.