[SCSI] ch: Add scsi type modalias

The ch module is missing the scsi:t-0x08* alias that would cause it to
be auto-loaded when a device of that type if found by udev, requiring
udev to have a specific rule just for this one module.  This patch adds
the alias.

Signed-off-by: Scott James Remnant <scott@canonical.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>