i965: Delete now dead persample_2x FS program key flag.

This was only used by the old gl_SampleID calculations.  The new code
doesn't need to handle 2x specially.

v2: Delete it from the Vulkan driver, too.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>

src/intel/vulkan/anv_pipeline.c

@@ -287,9 +287,6 @@ populate_wm_prog_key(const struct brw_device_info *devinfo,
        * harmless to compute it and then let dead-code take care of it.
        */
       key->persample_shading = info->pMultisampleState->sampleShadingEnable;
-      if (key->persample_shading)
-         key->persample_2x = info->pMultisampleState->rasterizationSamples == 2;
-
       key->compute_pos_offset = info->pMultisampleState->sampleShadingEnable;
       key->compute_sample_id = info->pMultisampleState->sampleShadingEnable;
    }