pwm: omap-dmtimer: Return -EPROBE_DEFER if no dmtimer platform data

If a pwm-omap-dmtimer is probed before the dmtimer it uses, the platform
data won't be set yet.

Fixes: ac30751d ("ARM: OMAP: pdata-quirks: Remove unused timer pdata")
Cc: <stable@vger.kernel.org> # 4.17+
Signed-off-by: David Rivshin <drivshin@allworx.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Ladislav Michl <ladis@linux-mips.org>
Tested-by: Andreas Kemnade <andreas@kemnade.info>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-omap-dmtimer.c

@@ -264,8 +264,9 @@ static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
 
 	timer_pdata = dev_get_platdata(&timer_pdev->dev);
 	if (!timer_pdata) {
-		dev_err(&pdev->dev, "dmtimer pdata structure NULL\n");
-		ret = -EINVAL;
+		dev_dbg(&pdev->dev,
+			 "dmtimer pdata structure NULL, deferring probe\n");
+		ret = -EPROBE_DEFER;
 		goto put;
 	}