scsi: ufs-bsg: Fix runtime PM imbalance on error

When ufs_bsg_alloc_desc_buffer() returns an error code, a pairing runtime
PM usage counter decrement is needed to keep the counter balanced.

Link: https://lore.kernel.org/r/20200522045932.31795-1-dinghao.liu@zju.edu.cn
Fixes: 74e5e468 (scsi: ufs-bsg: Wake the device before sending raw upiu commands)
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs_bsg.c

@@ -106,8 +106,10 @@ static int ufs_bsg_request(struct bsg_job *job)
 		desc_op = bsg_request->upiu_req.qr.opcode;
 		ret = ufs_bsg_alloc_desc_buffer(hba, job, &desc_buff,
 						&desc_len, desc_op);
-		if (ret)
+		if (ret) {
+			pm_runtime_put_sync(hba->dev);
 			goto out;
+		}
 
 		/* fall through */
 	case UPIU_TRANSACTION_NOP_OUT: