[SCSI] qla2xxx: Correct synchronization issues during rport addition/deletion.

The driver can typically detect port-loss during an
interrupt context (i.e. via interrogation of a status IOCB's
completion status [CS_PORT_LOGGED_OUT].  Due to the calling
requirements of the fc_rport APIs, the driver would defer
removal of the device to the default workqueue.  If the
work-item was preceded by an event which caused the port to
obtain visibility (relogin successful, target re-logged into
the topology), deferred removal could inadvertently drop the
rport.  The code also no longer defers removal via the
default workqueue, instead opting for use of the driver's
own DPC thread.

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