leds: leds-ot200: Use devm_led_classdev_register

Use resource-managed function devm_led_classdev_register
instead of led_classdev_register to make the error path simpler.
The goto is replaced with direct return, unneeded label err is
dropped. Also, remove redundant ot200_led_remove.

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>