vc4: Simplify the load/store utile functions.

They now have less of a dependency on the cpp, and don't have to do a
divide.

Hacking up mesa-demos teximage to do only one subtest and not draw
points, I saw 1024x1024 glTexSubImage2D() improve by 4.86939% +/-
1.40408% (n=30) and glGetTexImage() by 2.18978% +/- 0.140268% (n=5).
1 file changed