media: lirc-func.rst: new ioctl LIRC_GET_REC_TIMEOUT is not in a separate file

This fixes the warning:

Documentation/media/uapi/rc/lirc-func.rst:9: WARNING: toctree contains reference to nonexisting document 'media/uapi/rc/lirc-get-rec-timeout'

The ioctl is documented in lirc-set-rec-timeout.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>