serial: omap: enable PM runtime only when its fully configured

If earlyprintk is enabled and current UART is console port the platform
code can mark it as RPM_ACTIVE to sync real IP state with PM Runtime and
avoid resuming of already active device, but now, driver initialization
will be performed in the wrong way:

	pm_runtime_enable(&pdev->dev);
    <-- PM runtime alowed (device state RPM_ACTIVE)
	if (omap_up_info->autosuspend_timeout == 0)
		omap_up_info->autosuspend_timeout = -1;
	device_init_wakeup(up->dev, true);
	pm_runtime_use_autosuspend(&pdev->dev);
	<-- update_autosuspend() will be called and it will disable device
        (device state RPM_SUSPENDED)
	pm_runtime_set_autosuspend_delay(&pdev->dev,
			omap_up_info->autosuspend_timeout);
	<-- update_autosuspend() will be called which will re-enable device
        (device state RPM_ACTIVE), because autosuspend_timeout < 0

	pm_runtime_irq_safe(&pdev->dev);
	pm_runtime_get_sync(&pdev->dev);
	<-- will do nothing

Such behavior isn't expected by OMAP serial drivers and causes
unpredictable calls of serial_omap_runtime_suspend() and
serial_omap_runtime_resume().

Hence, fix it by allowing PM runtime only after all its parameters are
configured.

CC: Tony Lindgren <tony@atomide.com>
CC: Rajendra Nayak <rnayak@ti.com>
CC: Felipe Balbi <balbi@ti.com>
CC: Kevin Hilman <khilman@linaro.org>
Tested-by: NMark Jackson <mpfj-list@newflow.co.uk>
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/omap-serial.c

@@ -1506,7 +1506,6 @@ static int serial_omap_probe(struct platform_device *pdev)
 	INIT_WORK(&up->qos_work, serial_omap_uart_qos_work);
 
 	platform_set_drvdata(pdev, up);
-	pm_runtime_enable(&pdev->dev);
 	if (omap_up_info->autosuspend_timeout == 0)
 		omap_up_info->autosuspend_timeout = -1;
 	device_init_wakeup(up->dev, true);
@@ -1515,6 +1514,8 @@ static int serial_omap_probe(struct platform_device *pdev)
 			omap_up_info->autosuspend_timeout);
 
 	pm_runtime_irq_safe(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	pm_runtime_get_sync(&pdev->dev);
 
 	omap_serial_fill_features_erratas(up);