Patch from Peter Teichmann

vidc_mksound causes the kernel to crash badly when executed. As it does not do anything useful I did not take the time to find out why, but removed it.

The vidc does have an external reference clock that is used to generate 44100/20050/10025kHz sample rates. The code is changed in a way that it uses that reference clock that can better approximate the desired clock.

If we can approximate the desired rate to more than 1/256 accuracy, we return the desired rate instead of the real rate. This is to assist using some programs that for instance believe they need exacly 8kHz which we can not have, but we can have 8.018kHz which is pretty close so that nobody would notice the difference.