drm/i915: add new gen12 dgfx platform macro

Add a new macro for GEN12 platforms to be grouped under dgfx feature
set.
Signed-off-by: NStuart Summers <stuart.summers@intel.com>
Signed-off-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191024195122.22877-2-lucas.demarchi@intel.com

drivers/gpu/drm/i915/i915_pci.c

@@ -822,6 +822,10 @@ static const struct intel_device_info intel_tigerlake_12_info = {
 	.has_rps = false, /* XXX disabled for debugging */
 };
 
+#define GEN12_DGFX_FEATURES \
+	GEN12_FEATURES, \
+	.is_dgfx = 1
+
 #undef GEN
 #undef PLATFORM