drm/i915: Count engine instances per uabi class

This will be useful to have at hand in a following patch.

Signed-off-by: Tvrtko Ursulin <[e-mail]>
Reviewed-by: Umesh Nerlige Ramappa <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/gt/intel_engine_user.c

···
 void intel_engines_driver_register(struct drm_i915_private *i915)
 {
 	struct legacy_ring ring = {};
-	u8 uabi_instances[5] = {};
 	struct list_head *it, *next;
 	struct rb_node **p, *prev;
 	LIST_HEAD(engines);
···
 		GEM_BUG_ON(engine->class >= ARRAY_SIZE(uabi_classes));
 		engine->uabi_class = uabi_classes[engine->class];
 
-		GEM_BUG_ON(engine->uabi_class >= ARRAY_SIZE(uabi_instances));
-		engine->uabi_instance = uabi_instances[engine->uabi_class]++;
+		GEM_BUG_ON(engine->uabi_class >=
+			   ARRAY_SIZE(i915->engine_uabi_class_count));
+		engine->uabi_instance =
+			i915->engine_uabi_class_count[engine->uabi_class]++;
 
 		/* Replace the internal name with the final user facing name */
 		memcpy(old, engine->name, sizeof(engine->name));
···
 		int class, inst;
 		int errors = 0;
 
-		for (class = 0; class < ARRAY_SIZE(uabi_instances); class++) {
-			for (inst = 0; inst < uabi_instances[class]; inst++) {
+		for (class = 0; class < ARRAY_SIZE(i915->engine_uabi_class_count); class++) {
+			for (inst = 0; inst < i915->engine_uabi_class_count[class]; inst++) {
 				engine = intel_engine_lookup_user(i915,
 								  class, inst);
 				if (!engine) {

drivers/gpu/drm/i915/i915_drv.h

···
 	struct pci_dev *bridge_dev;
 
 	struct rb_root uabi_engines;
+	unsigned int engine_uabi_class_count[I915_LAST_UABI_ENGINE_CLASS + 1];
 
 	struct resource mch_res;