leds: lgm-sso: Put fwnode in any case during ->probe()

fwnode_get_next_child_node() bumps a reference counting of a returned variable.
We have to balance it whenever we return to the caller.

All the same in fwnode_for_each_child_node() case.

Fixes: c3987cd2 ("leds: lgm: Add LED controller driver for LGM SoC")
Cc: Amireddy Mallikarjuna reddy <mallikarjunax.reddy@linux.intel.com>
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>