[SCSI] qla2xxx: Fix issue where final flash-segment updates were falling into the slow-path write handler.

Original implementation would not use the burst-write mechanisms
for requests equal to OPTROM_BURST_DWORDS transfer dwords.
Signed-off-by: NAndrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>