serial: 8250: omap: Move pm_runtime_get_sync

Currently in omap_8250_shutdown, the dma->rx_running flag is
set to zero in omap_8250_rx_dma_flush. Next pm_runtime_get_sync
is called, which is a runtime resume call stack which can
re-set the flag. When the call omap_8250_shutdown returns, the
flag is expected to be UN-SET, but this is not the case. This
is causing issues the next time UART is re-opened and
omap_8250_rx_dma is called. Fix by moving pm_runtime_get_sync
before the omap_8250_rx_dma_flush.

cc: stable@vger.kernel.org
Fixes: 0e31c8d ("tty: serial: 8250_omap: add custom DMA-RX callback")
Signed-off-by: Bin Liu <b-liu@ti.com>
[Judith: Add commit message]
Signed-off-by: Judith Mendez <jm@ti.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20241031172315.453750-1-jm@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: liubiin

drivers/tty/serial/8250/8250_omap.c

@@ -776,12 +776,12 @@ static void omap_8250_shutdown(struct uart_port *port)
 	struct uart_8250_port *up = up_to_u8250p(port);
 	struct omap8250_priv *priv = port->private_data;
 
+	pm_runtime_get_sync(port->dev);
+
 	flush_work(&priv->qos_work);
 	if (up->dma)
 		omap_8250_rx_dma_flush(up);
 
-	pm_runtime_get_sync(port->dev);
-
 	serial_out(up, UART_OMAP_WER, 0);
 	if (priv->habit & UART_HAS_EFR2)
 		serial_out(up, UART_OMAP_EFR2, 0x0);