backlight: l4f00242t03: fix error handling in l4f00242t03_probe

Error handling fixes:
1. In the case of kzalloc failure, simple return -ENOMEM instead of goto
   err. ( priv is NULL in this case )
2. In the case of gpio_request fail for reset_gpio and data_enable_gpio,
   properly release resources by goto err and err2 respectively.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>