[SCSI] qla2xxx: Add QoS support.

Set the number of request queues to the module paramater
ql2xmaxqueues.  Each vport gets a request queue. The QoS value
set to the request queues determines priority control for queued
IOs. If QoS value is not specified, the vports use the default
queue 0.

Signed-off-by: Anirban Chakraborty <anirban.chakraborty@qlogic.com>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>