asahi: add missing lowerings

not sure how this worked before.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29607>

src/asahi/lib/agx_bg_eot.c

@@ -38,6 +38,7 @@ agx_compile_bg_eot_shader(struct agx_bg_eot_cache *cache, nir_shader *shader,
       agx_nir_lower_tilebuffer(shader, tib, NULL, &bindless_base, NULL);
       agx_nir_lower_monolithic_msaa(shader, tib->nr_samples);
       agx_nir_lower_multisampled_image_store(shader);
+      agx_nir_lower_texture(shader);
 
       nir_shader_intrinsics_pass(
          shader, lower_tex_handle_to_u0,

src/asahi/lib/agx_nir_lower_tilebuffer.c

@@ -172,7 +172,7 @@ dim_for_rt(nir_builder *b, unsigned nr_samples, nir_def **sample)
       *sample = nir_imm_intN_t(b, 0, 16);
       return GLSL_SAMPLER_DIM_2D;
    } else {
-      *sample = nir_load_sample_id(b);
+      *sample = nir_u2u16(b, nir_load_sample_id(b));
       b->shader->info.fs.uses_sample_shading = true;
       return GLSL_SAMPLER_DIM_MS;
    }