mfd: Implicitly register mc13xxx led subdevice

A led subdevice is registered now iff the corresponding platform data is
available. Without platform data the device isn't usable so this is a
sound check.
Signed-off-by: NPhilippe Rétornaz <philippe.retornaz@epfl.ch>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/mc13xxx-core.c

@@ -759,7 +759,7 @@ static int mc13xxx_probe(struct spi_device *spi)
 	if (pdata->flags & MC13XXX_USE_TOUCHSCREEN)
 		mc13xxx_add_subdevice(mc13xxx, "%s-ts");
 
-	if (pdata->flags & MC13XXX_USE_LED)
+	if (pdata->leds)
 		mc13xxx_add_subdevice_pdata(mc13xxx, "%s-led",
 				pdata->leds, sizeof(*pdata->leds));