[SCSI] gdth: scan for scsi devices

The patch: "gdth: switch to modern scsi host registration"

missed one simple fact when moving a way from scsi_module.c.
That is to call scsi_scan_host() on the probed host.
With this the gdth driver from 2.6.24 is again able to
see drives and boot.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Tested-by: Joerg Dorchain <joerg@dorchain.net>
Tested-by: Stefan Priebe <s.priebe@allied-internet.ag>
Tested-by: Jon Chelton <jchelton@ffpglobal.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>