drm/i915: use drm_modeset_lock_assert_held() in intel_connector_get_pipe()

In the intel_connector_get_pipe() function, we check if
connection_mutex is held and generate our own WARN_ON if that's the
case.  Instead of generating a non-standard warning for a mutex issue,
we should use the standard lockdep framework.

Change the function to use drm_modeset_lock_assert_held() instead.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Link: https://lore.kernel.org/r/20250520095408.1310440-1-luciano.coelho@intel.com

Author: lucacoelho

drivers/gpu/drm/i915/display/intel_connector.c

@@ -209,8 +209,7 @@ enum pipe intel_connector_get_pipe(struct intel_connector *connector)
 {
 	struct intel_display *display = to_intel_display(connector);
 
-	drm_WARN_ON(display->drm,
-		    !drm_modeset_is_locked(&display->drm->mode_config.connection_mutex));
+	drm_modeset_lock_assert_held(&display->drm->mode_config.connection_mutex);
 
 	if (!connector->base.state->crtc)
 		return INVALID_PIPE;