devmapper: Remove unnecessary condition check in updatePoolTransactionId()

Currently updatePoolTransactionId() checks if NewTransactionId and
TransactionId are not same only then update the transaction Id in pool. This
check is redundant. Currently we call updatePoolTransactionId() only from
two places and both of these first allocate a new transaction Id.

Also updatePoolTransactionId() should only be called after allocating
new transaction Id otherwise it does not make any sense.

Remove the redundant check and reduce confusion.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -205,12 +205,10 @@ func (devices *DeviceSet) allocateTransactionId() uint64 {
 }
 
 func (devices *DeviceSet) updatePoolTransactionId() error {
-	if devices.NewTransactionId != devices.TransactionId {
-		if err := devicemapper.SetTransactionId(devices.getPoolDevName(), devices.TransactionId, devices.NewTransactionId); err != nil {
-			return fmt.Errorf("Error setting devmapper transaction ID: %s", err)
-		}
-		devices.TransactionId = devices.NewTransactionId
+	if err := devicemapper.SetTransactionId(devices.getPoolDevName(), devices.TransactionId, devices.NewTransactionId); err != nil {
+		return fmt.Errorf("Error setting devmapper transaction ID: %s", err)
 	}
+	devices.TransactionId = devices.NewTransactionId
 	return nil
 }