[SCSI] qla2xxx: Disable port-type RSCN handling via driver state-machine.

Given the semantic changes in both the device-model and
fc-transport APIs, the driver's handling of port-type RSCNs
via a series of ADISCs and PLOGIs can cause series of
badness ranging from unexpectedly device loss to devices not
being discovered.

In the interim, disable (via a module-parameter) this
feature and allow RSCN management to continue to occur
within the driver's DPC thread.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>