[SCSI] pm8001: enhance IOMB process modules

We set interupt cascading count of outbound queue to get better
performance, correct some unnecessary return values and some noisy
print messages.  patch attached.
Signed-off-by: NJack Wang <jack_wang@usish.com>
Signed-off-by: NLindar Liu <lindar_liu@usish.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/pm8001/pm8001_sas.h

@@ -119,7 +119,7 @@ struct pm8001_dispatch {
 	void (*chip_rst)(struct pm8001_hba_info *pm8001_ha);
 	int (*chip_ioremap)(struct pm8001_hba_info *pm8001_ha);
 	void (*chip_iounmap)(struct pm8001_hba_info *pm8001_ha);
-	void (*isr)(struct pm8001_hba_info *pm8001_ha);
+	irqreturn_t (*isr)(struct pm8001_hba_info *pm8001_ha);
 	u32 (*is_our_interupt)(struct pm8001_hba_info *pm8001_ha);
 	int (*isr_process_oq)(struct pm8001_hba_info *pm8001_ha);
 	void (*interrupt_enable)(struct pm8001_hba_info *pm8001_ha);