media: nuvoton-cir: remove setting tx carrier functions

Since this driver could never transmit IR, setting the tx carrier makes
no sense.

Fixes: 87284271 ("media: rc: nuvoton: remove rudimentary transmit functionality")
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>