[SCSI] ide-scsi: Close narrow race in release

We were releasing the block devices before removing the host, so commands
could still be coming in which would cause a panic.  Just remove the
host before releasing the block devices to close this race.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>