drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe

During device boot, the HPD interrupt could be triggered before the DRM
subsystem registers it6505 as a DRM bridge. In such cases, the driver
tries to access AUX channel and causes NULL pointer dereference.
Initializing the AUX channel earlier to prevent such error.

Fixes: b5c84a9e ("drm/bridge: add it6505 driver")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013110411.1674359-2-treapking@chromium.org

drivers/gpu/drm/bridge/ite-it6505.c

@@ -2871,10 +2871,7 @@ static int it6505_bridge_attach(struct drm_bridge *bridge,
 	}
 
 	/* Register aux channel */
-	it6505->aux.name = "DP-AUX";
-	it6505->aux.dev = dev;
 	it6505->aux.drm_dev = bridge->dev;
-	it6505->aux.transfer = it6505_aux_transfer;
 
 	ret = drm_dp_aux_register(&it6505->aux);
 
@@ -3354,6 +3351,11 @@ static int it6505_i2c_probe(struct i2c_client *client,
 	debugfs_init(it6505);
 	pm_runtime_enable(dev);
 
+	it6505->aux.name = "DP-AUX";
+	it6505->aux.dev = dev;
+	it6505->aux.transfer = it6505_aux_transfer;
+	drm_dp_aux_init(&it6505->aux);
+
 	it6505->bridge.funcs = &it6505_bridge_funcs;
 	it6505->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
 	it6505->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |