drm/i915/tgl: add gen12 to stolen initialization

Add case for gen == 12 and add MISSING_CASE() for future gens. We were
already handling gen12 as the default, so this doesn't change the
current behavior.

BSpec: 19481 and 44980

Cc: CQ Tang <cq.tang@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190904213419.27547-7-jose.souza@intel.comSigned-off-by: José Roberto de Souza <jose.souza@intel.com>

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

@@ -425,8 +425,11 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv)
 			bdw_get_stolen_reserved(dev_priv,
 						&reserved_base, &reserved_size);
 		break;
-	case 11:
 	default:
+		MISSING_CASE(INTEL_GEN(dev_priv));
+		/* fall-through */
+	case 11:
+	case 12:
 		icl_get_stolen_reserved(dev_priv, &reserved_base,
 					&reserved_size);
 		break;