tty: serial: OMAP: Fix oops due to NULL pdata in DT boot

The following commit: be4b0281956c5cae4f63f31f11d07625a6988766
(tty: serial: OMAP: block idle while the UART is transferring data in PIO mode),
is introducing an oops if OMAP is booted using device tree blob because
the pdata will not be initialized.

Check if pdata is set before de-referencing it.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Reviewed-by: Paul Walmsley <paul@pwsan.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/omap-serial.c

@@ -159,7 +159,7 @@ static void serial_omap_stop_tx(struct uart_port *port)
 		serial_out(up, UART_IER, up->ier);
 	}
 
-	if (!up->use_dma && pdata->set_forceidle)
+	if (!up->use_dma && pdata && pdata->set_forceidle)
 		pdata->set_forceidle(up->pdev);
 
 	pm_runtime_mark_last_busy(&up->pdev->dev);
@@ -298,7 +298,7 @@ static void serial_omap_start_tx(struct uart_port *port)
 	if (!up->use_dma) {
 		pm_runtime_get_sync(&up->pdev->dev);
 		serial_omap_enable_ier_thri(up);
-		if (pdata->set_noidle)
+		if (pdata && pdata->set_noidle)
 			pdata->set_noidle(up->pdev);
 		pm_runtime_mark_last_busy(&up->pdev->dev);
 		pm_runtime_put_autosuspend(&up->pdev->dev);
@@ -1613,7 +1613,7 @@ static int serial_omap_runtime_resume(struct device *dev)
 	struct uart_omap_port *up = dev_get_drvdata(dev);
 	struct omap_uart_port_info *pdata = dev->platform_data;
 
-	if (up) {
+	if (up && pdata) {
 		if (pdata->get_context_loss_count) {
 			u32 loss_cnt = pdata->get_context_loss_count(dev);