drm/i915/rps: fix stale reference to i915->irq_lock

The RPS code has been switched from using i915->irq_lock to gt->irq_lock
years ago in commit d762043 ("drm/i915: Extract GT powermanagement
interrupt handling"). Fix the stale comment referencing i915->irq_lock,
which has also ceased to exist.

Reported-by: Gustavo Sousa <gustavo.sousa@intel.com>
Closes: https://lore.kernel.org/r/174656703321.1401.8627403371256302933@intel.com
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://lore.kernel.org/r/20250507083136.1987023-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: jnikula

drivers/gpu/drm/i915/gt/intel_rps_types.h

@@ -57,7 +57,7 @@ struct intel_rps {
 
 	/*
 	 * work, interrupts_enabled and pm_iir are protected by
-	 * i915->irq_lock
+	 * gt->irq_lock
 	 */
 	struct timer_list timer;
 	struct work_struct work;