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

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.