i965: Don't disable CCS for RT dependencies when dispatching compute.

Compute shaders don't have access to the framebuffer, so there's no
point in worrying whether a texture is bound as a render target.

This saves a bunch of resolves in GFXBench4 Manhattan 3.1, but doesn't
seem to impact performance at all, at least on Apollolake.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
(cherry picked from commit 583ce96c)