serial: bfin_5xx: need to disable DMA TX interrupt too

If we don't disable the DMA TX channel, an inopportune timeout will
trigger the interrupt handler and may cause a dead lock with the spin_lock.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/serial/bfin_5xx.c

@@ -488,6 +488,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
 {
 	int x_pos, pos;
 
+	dma_disable_irq(uart->tx_dma_channel);
 	dma_disable_irq(uart->rx_dma_channel);
 	spin_lock_bh(&uart->port.lock);
 
@@ -521,6 +522,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
 	}
 
 	spin_unlock_bh(&uart->port.lock);
+	dma_enable_irq(uart->tx_dma_channel);
 	dma_enable_irq(uart->rx_dma_channel);
 
 	mod_timer(&(uart->rx_dma_timer), jiffies + DMA_RX_FLUSH_JIFFIES);