[SCSI] qla4xxx: regression - add start scan callout

We are seeing EXIST errors from sysfs during device addition.
We need a start scan callout so we do not start scanning sessions
found during hba setup, before the async scsi scan code is ready.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: David C Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>