[SCSI] megaraid_sas: Add poll mechanism to megaraid sas driver

Add Poll_wait mechanism to SAS-2 MegaRAID SAS Linux driver. Driver
will wakeup poll after the driver get event from MegaRAID SAS FW.

Signed-off-by Bo Yang<bo.yang@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 0d03324..900359f 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -1120,6 +1120,7 @@
 	struct tasklet_struct isr_tasklet;
 
 	u8 flag;
+	u8 unload;
 	unsigned long last_time;
 
 	struct timer_list io_completion_timer;