tu: Don't use rasterizationSamples when enabling sample shading

From the spec language, it seems like this change wasn't strictly
required and is just an optimization for when minSampleShading would
be small enough to allow one sample per pixel. However
rasterizationSamples will soon possibly be dynamic, and I don't think we
should keep this around.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18912>

src/freedreno/vulkan/tu_pipeline.c

@@ -2629,8 +2629,7 @@ tu_pipeline_shader_key_init(struct ir3_shader_key *key,
     * just checked in tu6_emit_fs_inputs.  We will also copy the value to
     * tu_shader_key::force_sample_interp in a bit.
     */
-   if (msaa_info && msaa_info->sampleShadingEnable &&
-       (msaa_info->minSampleShading * msaa_info->rasterizationSamples) > 1.0f)
+   if (msaa_info && msaa_info->sampleShadingEnable)
       key->sample_shading = true;
 }