[media] rc: nuvoton: use managed versions of rc_allocate_device and rc_register_device

Simplify the remove function and the error path in the probe function by
using the managed versions of rc_allocate_device and rc_register_device.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>