leds: lp50xx: Fix an error handling path in 'lp50xx_probe_dt()'

leds: lp50xx: Fix an error handling path in 'lp50xx_probe_dt()'

In case of memory allocation failure, we must release some resources as
done in all other error handling paths of the function.

'goto child_out' instead of a direct return so that 'fwnode_handle_put()'
is called when we break out of a 'device_for_each_child_node' loop.

Fixes: 242b81170fb8 ("leds: lp50xx: Add the LP50XX family of the RGB LED driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>