fake tuner id change

I have no idea if it's useful to anyone but me. I sent it to mlord and he can decide whether to include it or not, but in the meantime, this allows an ioctl to change the tuner id in the fake tuner case. Note that (I expect, I haven't checked) that the player software checks it once, when it starts, so if you use the ioctl to change it, you have to let init respawn the player so it notices.

Cheap problem to exercise the ioctl.