scsi: libsas: fix memory leak in sas_smp_get_phy_events()

We've got a memory leak with the following producer:

while true;
do cat /sys/class/sas_phy/phy-1:0:12/invalid_dword_count >/dev/null;
done

The buffer req is allocated and not freed after we return. Fix it.

Fixes: 2908d778ab ("[SCSI] aic94xx: new driver")
Signed-off-by: Jason Yan <yanaijie@huawei.com>
CC: John Garry <john.garry@huawei.com>
CC: chenqilin <chenqilin2@huawei.com>
CC: chenxiang <chenxiang66@hisilicon.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libsas/sas_expander.c

@@ -695,6 +695,7 @@ int sas_smp_get_phy_events(struct sas_phy *phy)
 	phy->phy_reset_problem_count = scsi_to_u32(&resp[24]);
 
  out:
+	kfree(req);
 	kfree(resp);
 	return res;