[media] media: rc: nuvoton-cir: remove unneeded lock

chip_major / chip_minor are accessed sequentially in probe only.
Therefore no lock is needed.

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