i965: Remove linear_color for GL_PERSPECTIVE_CORRECTION_HINT.

From the GL 2.1 spec:

   "Required perspective-correct interpolation for all fragment
    attributes except depth in sections 3.4.1 and 3.5.1, effectively
    making GL PERSPECTIVE CORRECT HINT a no-op."

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
7 files changed