ttn: handle GLSL_SAMPLER_DIM_SUBPASS_MS case

Fixes a warning.

Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
diff --git a/src/gallium/auxiliary/nir/tgsi_to_nir.c b/src/gallium/auxiliary/nir/tgsi_to_nir.c
index d01e458..f50a5a6 100644
--- a/src/gallium/auxiliary/nir/tgsi_to_nir.c
+++ b/src/gallium/auxiliary/nir/tgsi_to_nir.c
@@ -1341,6 +1341,7 @@
       instr->coord_components = 3;
       break;
    case GLSL_SAMPLER_DIM_SUBPASS:
+   case GLSL_SAMPLER_DIM_SUBPASS_MS:
       unreachable("invalid sampler_dim");
    }