[SCSI] qla4xxx: Remove AF_DPC_SCHEDULED flag from ha.

Since queue_work does not requeue, there is no need to check
if a work is in progress using the AF_DPC_SCHEDULED flag.
queue_work would return if work is pending without adding the
work, do_dpc would again get invoked from qla4xxx_timer if
there is still DPC flags set.

Signed-off-by: Lalit Chandivade <lalit.chandivade@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <jbottomley@parallels.com>