Add support for async scanning
Notes: This is the async scan patch to our driver from Matthew Wilcox.
The async scan logic is still subject to errors in insmod/rmmod, as
the async scan threads don't get shutdown when the module unloads
underneath them. See http://marc.info/?l=linux-scsi&m=117551999925582&w=2
Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>