update to match binary

[ThePlayerRolo]

As it was before this pull request in Sky when using a cube map TRILINEAR mip mapping was used

However, on further investigation, it seems that the actual mipmap setting used was BILINEAR_NO_MIPMAP

On every interpolate variable in this function it uses 2, which according the PDB's is BILINEAR_NO_MIPMAP

This leads me to the idea that this was either A. changed due to a bug or B. wrong version
You see, a bug exists if you try to use this version of g3d sky's cubemap due to TRILINEAR mipmapping which results in something like this:

However, setting it to BILINEAR_NO_MIPMAP fixes this issue (this is how I learned about this.)

Though it could also be due to a wrong version since ToneMap also needed to be added.

Either way, the correct and matching solution is to change it, so thats what this PR does