i965/gen8: Factor out texture surface state set-up from gen8_update_texture_surface().
i965/gen8: Factor out texture surface state set-up from gen8_update_texture_surface().

This moves most of the surface state set-up logic that can be shared
between textures and shader images to a separate function.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler