vc4/v3d: stop adding NORAST when SHADERDB debug option is used

Right now if we use the option SHADERDB, NORAST is added automatically. There's no comment justifying it, neither a lot of info on the commits that added that. But I guess that the purpose is that SHADERDB option is assumed to be used only to gather shader-db stats, so setting setting NORAST would allow to get those dumps faster.

But adding debug options automatically can be confusing, as we could get a behaviour that we were not expecting. At least I needed to check why using SHADERDB was getting a black screen. And if we want to get this behaviour, we can easily add manually the NORAST.

Finally, v3dv doesn't support NORAST right now (and we don't have immediate plans to implement it), so it is somewhat inconsistent to get different behaviour from the same debug option from the two drivers.