leds: lgm-sso: Propagate error codes from callee to caller

leds: lgm-sso: Propagate error codes from callee to caller

The one of the latest change to the driver reveals the problem that
the error codes from callee aren't propagated to the caller of
__sso_led_dt_parse(). Fix this accordingly.

Fixes: 9999908ca1ab ("leds: lgm-sso: Put fwnode in any case during ->probe()")
Fixes: c3987cd2bca3 ("leds: lgm: Add LED controller driver for LGM SoC")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>