leds: mc13783: Fix "uninitialized variable" warning

drivers/leds/leds-mc13783.c: In function 'mc13xxx_led_probe':
drivers/leds/leds-mc13783.c:195:2: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Bryan Wu <cooloney@gmail.com>