drm/i915/i915_drv: Use proper parameter naming in for_each_engine()

for_each_engine() loops through engines in the GT, not in
dev_priv.  Because it's misleading, call it "gt__" instead of
"dev_priv__".
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230421190026.294208-2-andi.shyti@linux.intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -381,11 +381,11 @@ static inline struct intel_gt *to_gt(struct drm_i915_private *i915)
 }
 
 /* Simple iterator over all initialised engines */
-#define for_each_engine(engine__, dev_priv__, id__) \
+#define for_each_engine(engine__, gt__, id__) \
 	for ((id__) = 0; \
 	     (id__) < I915_NUM_ENGINES; \
 	     (id__)++) \
-		for_each_if ((engine__) = (dev_priv__)->engine[(id__)])
+		for_each_if ((engine__) = (gt__)->engine[(id__)])
 
 /* Iterator over subset of engines selected by mask */
 #define for_each_engine_masked(engine__, gt__, mask__, tmp__) \